A popup is a good suggestion for starting out on a budget. It provides a significant improvement in comfort and convenience over a tent, while being pretty friendly on the budget. (A tent is, of course, also a viable and very economical option.)
As motorhomes go, class C's are relatively economical to keep operating as far as the chassis goes. The majority are built on Ford van chassis, and parts and service for them are readily available and comparatively affordable, and the chassis themselves are pretty reliable with basic routine maintenance. That being said, the routine maintenance is not free, and it's wise to expect some will need to be done sooner or later--probably sooner--for most any used unit you get that's more than a very few years old. Tires often need replacement due to age rather than treadwear, after around seven years or so. Brakes often need service for similar reasons.
The rest of a motorhome, the house part and its systems, will generally need some more or less constant tinkering and fixing of minor odds and ends. If you're handy, or willing to become handy, a lot of that can be done on one's own. You basically are getting a cheaply-constructed apartment that is subjected to continuous seismic activity when you're traveling, and that's rough on things.
That all being said, there is something very special about travel in a motorhome. Having everything you need for a home at hand in your vehicle is just a really cool and handy thing. Pulling over to get a glass of water, or a snack, or use the restroom, or whatever is extremely convenient.
I've generally found that traveling by car and staying in a motel is cheaper if I'm only staying someplace for a few days. For several days or a week or more at a destination, taking the motorhome often becomes more economical: the cost of gas is made up for by the savings in a campground vs. a motel. It's often not fair to compare them, though, as it's a different way to travel and some wonderful places to camp just don't have other lodging convenient (or vice-versa). But, for travel on a quite tight budget, an RV in my opinion doesn't make the most sense in a great many cases.