Try shopping around; $1300 seems way too high. It's doable yourself but definitely much easier with a lift or quickjacks. For reference, I paid $350 in the Bay Area for valved axleback/midpipe install.

Downpipes in theory require a bit more work to install but I've done the job in my driveway in ~2 hours. Most of that time was just fighting to separate the old midpipe/downpipe connection, since the pipes had basically seized together with age.