Basically - there are a bunch of cheaper motels in Yucca Valley, all are about equivalent.
I've spent a night or two at the motel that's just north of the Park intersection, I think it's this?
http://www.desertgold.com/highdesert/motel.html. It'll do. If I didn't camp, I guess that's what I'd do - it's close, and there's food nearby. There's a starbucks in yucca valley now, by the way.
For a nicer ('decent'?) place, there's a B&B just next to the theater in Joshua Tree, just as you come into town.
http://www.joshuatreeinn.com/ There's no equivalent to high / leaf season there, but on one random weekend when Scott & I were just going to grab a room, *all* the motels were full b/c of something at 29 palms (military base). So it's not a terrible idea to reserve ahead, but you'd probably be able to walk in just fine.
please bring me a california burrito from santana's. thankyouverymuch.