What do you mean by a "short-term" online business model?
I'm working on an online business model myself, but mine is definitely long-term.
Something that doesn't need to last more than 4months. So: quick to set up, something where SEO isn't really needed, not trying to make 10K a month, just supplement on the side.
Define the amount of money you wish to earn. That's an important detail, and will help us direct you. However, the classic suggestion will always be eBay. Buy up stuff that's cheap, locally, and repackage/resell it at a profit. One summer, I bought stuff from a local dollar store, and sold it for no less than $10 on eBay, repeatedly.
And, I still have a good eye. I just picked up a Harley Davidson SoftTail fuel tank for $10, through a local swap shop. I can easily make 30-50 times my money back. That's not a bad return on my investment, for a couple of minutes' work.
I can't imagine buying dollar-store crap for $10+ on eBay! What do you think could explain it?
First, you have to get past your prejudice. Not all stuff at a dollar store is crap.
Some, especially overstock items, can actually be quite nice. I had bought books, picture frames, and even "pink flamingos" for $1, listed them with decent photographs, and sold them for a substantial profit. Ceramics and carved stone items did particularly well, that summer.
My local Dollar Tree currently has solar-charged LED path lighting...for $1. I could *easily* buy them, package them into sets of 4, and sell them as a buy-it-now package deal for $15 or $20. It's EASY!
A friend of mine got started on eBay as a "survival job" while he was unemployed. Two years of unemployment, actually. He would go pick stuff out of dumpsters and resell the garbage on eBay. He had a singular talent for it, and made a sufficient living at it to avoid the "pinch" that most people would feel during 2 years of unemployment. "Half Price Books" did well for him, too.
The old saying is absolutely true. One man's trash REALLY IS another man's treasure.
I still do this with my shoes...yes, I list my old boots on eBay. I can, and occasionally even have, bought a pair of cowboy boots (fairly cheap at thrift stores in Texas), and listed them in the decorating/designer section on eBay, for crazy interior decorators to bid on, in New York and California. It's amazing what a decorator in the "big cities" will pay for "Heavily-worn, broken-in, genuine cowboy boots, from a small country town in Texas," if it's the right item for the rustic theme on their client's living room display shelves. You should see how much a worn out cowboy hat or chaps can go for!
The trick is having a good eye, and an ability to recognize potential.
(And, just for reference, I have a 100% positive feedback rating)
When you see something at a dollar store that you wish to resell do you buy just one or multiple items?
It depends on what it is, how far away the store is located (I live out in the country), and whether I expect them to get more. For reference, the "local" Dollar Tree I mentioned is 30 miles away.
Generally, I buy at least 5 of the items...random number, but it just "feels" right. Remember, this is resale, so you have to have an "inventory" of some sort.
You can sell pretty much anything on eBay, so long as it falls within their guidelines. Knives, for example, can be a tricky business.
One of the listings I saw (not one of mine) that brought a smile to my face, was someone selling origami. They were selling, essentially, individual sheets of typing paper for up to $5 each. Not a bad idea!
I admire your enterprise.
I would say this is your best bet. Ebay is an established brand and people are already going there to buy things. It would be hard to get enough traffic to your own site in just four months to justify doing your own thing.
Yard sales are always good places to pick up things. Look for things you can clean up or repair and get cheap. I heard of someone who deals just in golf clubs, mostly individual ones. A few clubs that have been sitting for years may be worthless to whoever is selling, but cleaned up it could be just the club soemone else is missing in their bag. I've also heard of a kid who does legos. He buys big bings of them cheap at yard sales and cleans them up. I don't know if you've checked the price of legos lately but those things are expensive.
Remember if you hit yard sales you may have to pass up a lot of stuff to be able to find a good buy. It's best if you can focus on a few categories so you can get to know them. I saw an old video camera at a yard sale once, 60's I think. So you'll want to know if that's something that would be 'vintage' that you could make a profit on, or if it would be junk and you'll end up with an old camera just sitting around your house because no one wants it.
And, don't worry if what you're selling is "manly." There are certain brands that *always* do well. Earlier I mentioned the Harley Davidson fuel tank...well, anything with the name Harley on it is highly desirable. Same goes for Star Trek.
One time I couldn't resist a BARBIE Dream House at a garage sale, for a whopping cost of $1. Yep, everything Barbie is collectible, too.
Realize, also, that PARTS can be very lucrative. Did your laptop die in the last electrical storm? What a shame! But there are people who sell individual keys for laptop keyboards, for around $2-$5 each. Look down at your keyboard, and do the math. And the LCD, or even the chassis, can bring significant cash.