We use Florida Sun Vacation Homes because they offer a discount of 15% if you are staying longer than 7 nights. We find that during certain seasons they are actually cheaper with the discount than units on VRBO. We've rented 4 times through them and always stay in Windsor Hills (usually in a 4 BR home).
I would check out the website or call their toll free number to check availability. I think with their discount, the rate should be within your budget.
Good luck with your search!
Awesome!!! Thank you! I checked out most of the other sites that were suggested, but since we arrive on a Friday and depart Sunday (9 days), there was not a lot of availability. But Florida Sun Vacation Homes had 2 that were perfect, great price, and I just booked a townhome! My kids were looking at the pictures, they are so excited. THANK YOU!!!