Do you always move just with your Yaris (as in, you have very little stuff and no furniture)? I put my bike in the uhaul trailer last time I moved, and braced it between furniture and with straps; worked fine.
Also, since your biking needs will be pretty simple, you can buy a very cheap and simple bike used on craigslist. Often with cheap stuff on craigslist/stuff at thrift stores, I think of it more like renting instead of buying. Buy a bike cheap for $100, sell it cheap at the end of the six months, and then do it again the next place. Even if you lose some money every time, it might be awhile before it's worth buying a rack.
Also - serious question - have you thought about just getting a skateboard/walking more? 2 miles and flat is almost to the point of not even requiring wheels, IMO. (Unless you also want your bike to haul stuff - but getting a bike trailer would just compound your problem with frequent moves).