Right inner drive shaft boot looking oily

This is a good site:

AXLE SHAFTS & JOINTS for 2010 Toyota Prius | Toyota Parts

Driver's side would be left side, and you still need to verify with mechanic if it's inner or outer boot: there's one CV joint near the engine, another out near the wheel. You might want to take the part numbers on the above link and google them, because it's not clear (at least to me) which is which. Google and see if you can get some verification, which is which. There's probably only an inner and outer type, but I'm really not sure. If there's 4 unique part numbers, then there probably is 4 actual types.

Also, if your mechanic says it's an inner CV boot leaking, I'd be a bit cautious: it might in fact be a seal at the transaxle failing. Just make sure. If it's thin oil just coating the area, might be the seal. If it's heavy grease, flung, then it's more likely the CV joint. Also if there's an obvious tear in the CV boot, oozing grease, that's your smoking gun.

Hmm: looked again, very likely there's ONE boot type, they sure make it confusing though. Part number is:

04437-47033