My shop would charge me about $2000 to swap in a used engine (engine itself is probably $750 from a big dismantler). At $1,000 you couldn't go wrong parting it out - you could easily get half that for your catalytic converter.
But I would generally advise a random person against buying a random 10+ year old Prius off the internet because there are a number of potential problems that can cost as much as the car if you take it to the "wrong" shop.
The exceptions:
1) You buy a mechanic's special with the intention of fixing & selling it for substantially more than your total investment.
2) You drive at least 15K miles/year AND one of the following
- are capable of doing substantial electrical/mechanical work yourself
- you have a good reputable Prius-specialist repair shop and the financial capacity to weather repeated $2,000 repairs without worry.
Even with a number of potential $2,000 repair bills lurking (priced from good/reputable Prius shops), an old Prius can still be an economical commuter because it is so thrifty on gas.
Gen2 is more reliable than the Gen 3 (2010-2015), but Gen 3 gets ~8% better gas mileage. A well-driven Honda Civic or Toyota Echo, which are much simpler to repair, could come pretty close to matching a Gen2's mpg unless you do a lot of idling with A/C on.
In about 4 years & 60,000 miles my used 2010 Prius has needed:
headgasket replacement @ 128,000 miles ($2050 including new plugs & cleaned manifold/egr)
EGR replacement @ 135,000 miles ($0 under California's extended emissions warranty)
Hybrid battery replacement @ ~155,000 miles ($2200 for new Chinese cells)
Hybrid battery replacement @ ~ 180,000 miles ($200 labor, battery was covered under 5 year warranty)
More normal maintenance:
13 5K PMs (oil change, tire rotations, etc) $70/ea =$910
1 set of tires @ 155K $350
1 12V battery replacement @ ~185K miles $160
5 sets Sylvania H11 bulbs (they only last 160 hours!) @ $30 = $150
Toyota hatch struts @ 190K miles $75
6 wiper blades (all 3 every 2 years) ~$10/ea = $60
2 sets front sway bar end links: $90
HVAC blower motor: $45
1 set "beamtech" LED H11 bulbs @ $40
2 engine air filters @ ~$10/ea = $20
2 cabin air filters @ ~$10/ea = $20
1 set of LED parking light bulbs @ $10
I've averaged 51.4 mpg driving economically but without doing any crazy hypermiling pulse & glide type stuff. Gas here has averaged $3.78 over the last 4 years (currently sitting around $5). $4575
Fixed costs:
Registration: $160 x 4 years = $640
Liability insurance: $460 x 4 years = $1840
Biennial Smog Checks: 2 x $75 = $150
Depreciation: $0 !!! (bought it for $7,000 in late 2017 and its current market value is still around $7,000).
Close to total ownership costs (missing random car wash supplies): ~$13,550
Mileage driven: ~62,000
Total cost per mile: $0.22
My brake booster is starting to go bad so I'll be looking at another $1000-2000 repair soon. Yes, for a brake booster! And that's from a reputable prius shop - you might pay $4500 from the dealership:
https://priuschat.com/threads/brake-...cement.191669/