nobody want's wheels sitting around unless you need a winter set....
That's probably your cheapest option that is not going to cause you issues. Cheaper aftermarket wheels have varying quality and from what I have gathered around here aren't comparable to OEM quality unless you want to spend some bucks. There is probably a happy medium but I wouldn't go absolute lowest end.
Check reviews if you go aftermarket. Undamaged used OEM wheels are almost certainly fine, just make sure to inspect.
No modifications will be done. Just looking for good looking wheels at a reasonable price.
I have two sets of wheels. The stock 16" alloys with "high performance" all seasons on them I kept for the winter. For the summer there is set of 17x7.5 Traklite Gears that will get new summer performance rubber in the spring before going on the car.
Just FYI the 3rd generation Mazda MX5 (2006 up to 2015) uses the same wheel specs more or less, so that gives you a wider range of wheels to choose from.
You'll ask about what size eventually, so....you need a wheel that has an offset somewhere between +50 and +40. The lower the number the further out the wheel will be in the wheel well. I believe the factory wheels are +50. Bolt circle is 114.3x5 just so you know what to look at. Factory 16x6.5" rims come with 205/60/16 tires, they will work on 7" wide rims too. If you want to go bigger, 17" or larger, you'll need to start looking at tires too. Tire Rack is a good source of information when choosing rims and tires.
When you are looking, keep a couple things in mind. Weight is a consideration. Stock 16" alloys are 19 lbs, look for that or less if possible. Light = better. Look into how the rim is made. Cast = cheap and heavy. Flow formed = better. Forged = best but $$$$$. Flow formed rims are plenty strong enough and not expensive. Figure on spending at least $150 each for a decent set of rims. Advanti Racing and Konig are good for not a lot of money.
Another thing to consider is the lug nuts. Many aftermarket rims don't have a lot of clearance for using a standard socket on the lugs. Regular lugs will work but you run a distinct risk of scratching the rims up. So, you use a set of lugs made just for this purpose. They are smaller diameter and use a splined socket supplied with the set. McGuard and Gorrilla are two names that come to mind right off.