Joe....Here is a partial list of RV parks in Yuma....without calling or visiting each website, there is no way to know what they offer or their rates.
Yuma RV ParksHere is one listed on craigslist :
May Avenue Park, however I know nothing about it.
And a private lot advertized on craigslist:
Private LotAnd another private Lot:
anotherAnd yet another:
another private lotWith your budget, IMO, your best bet in Yuma would be a private RV lot in the Foothills section, they are usually full hookup, with garbage service, but with no WiFi, no gym, but plenty of smooth, paved streets for walking...you share a 65x120' fenced, gated, graveled lot with another RV-er. These lots usually rent for $300 and up.
Finding a private lot in the Foothills is as simple as driving the streets looking for "for rent" sign and calling the listed number.
Regards
Gemstone