Replace Hybrid Battery Pack

2005 Prius; 148,000 miles; check engine light, brake warning light, and hybrid system warning light are all on. Advance Auto read the code as P0A80 -- "Replace Hybrid Battery Pack" -- and dealer confirmed that this is, in fact, what needs to happen. Problem is, that's a $3,500 job (incl. tax) at the dealership, and I won't be able to afford it for a couple of months. So my question is, can I still drive this car occasionally? It seems to run fine, the Energy Monitor shows a working hybrid system that is getting about 45 mpg. I have driven it to the dealer and back -- about 40 miles round trip -- with no problem, and the Service Manager thought an occasional drive was OK, but not to use it as a daily driver. The back seat HV fan seems to be on more than usual. I don't want to get stranded or mess something up. Does anyone have some knowledge of the risks here?