Tatras and MANs are all cool rigs, but not exactly cheap and spares are probably not easy to get. How about our very own fire trucks and garbage trucks? Just to name a few:
KME fire truck chassis
HME fire truck chassis
I have seen some of the above sold on various surplus auctions for the price of a new family sedan. Throw a nice camper (for example a used 18-22ft 5th wheel) on top of one of these rigs, and you got yourself an expedition vehicle for way less than 100 grand.