borrow o2 sockets at local autozone for free... just $15 returnable deposit.
for 1995 and earlier: only one sensor (before cat) at autozone.com is around $62.99 a piece delivered - cheapest i have scouted for bosch with oem type connectors, so its plug and play. if you get it at store, they charge $6 s&h
for 1996 and later: same before cat sensor as above, plus one more after cat. OEM, right guys, OEM after cat sensor for $142 delivered through UPS at autopartsworld.com -best value for money.
changed both sensors a week ago and turned out perfect!