The repeater systems I have seen have been in-building/ commercial grade (in other words expensive) but there may be some out there for personal use. Wilson may even have a repeater-only avail for less. & $300 is relatively cheap compared to what I've seen avail.
I also now remember seeing a repeater antenna system which I believe was for in-car. I'll have to see if I have some info somewhere. In the mean time, try a search for "repeater antenna" & see what turns up.
also, I beleive the antennas you stick on a window are called "patch" antennas.
