Without knowing your dates it would be hard to tell. You should avoid Friday and Saturday nighs since those ponts are usually at least double the other nights. I just priced out one night July 18 with two stdios at the CBR ( amoderate resort). That would cost you $346 for two studios one night. If you stayed at one of cheaper point DVC places - Old Key West- you could get a 2 bedroom Villa that is 1322 sq feet, with a full kitchen and washer and dryer for around $300 - 330 Sunday through Thursday. Friday and Saturday would run about $730 - 803. You need to understand the risk of renting since you would be renting from a DVC member and not Disney. I hope this helps.
The Old Key West studios are 376 sq feet and do not have a washer/dryer or kitchen. For the extra money I would go for the 2 bedroom and enjoy the extra room.
Dont forget that you can save time and money by having a full kitchen. Having the kitchen makes the trip a lot easier. For example we always buy a whole bunch of bottled water and take it with us to the parks. Kids are always eating, so much easier and less expensive to have some on hand. You can really save money and time by having breakfast in your room.
As someone else mentioned, make sure you understand the pros and cons of renting.