Replacement engine for 94 civic ex

[John]

My beloved 1994 civic may need a new engine (don't ask!) and I'm looking at
replacement engine possibilities.

Anyone know the going rate $$$ or good resellers for acquiring replacements
like these?

D16Z6 -- 1.6L, the standard vtec 125hp for civic ex
B18A1 -- 1.8L, Acura engine, 140hp popular with swaps
B18C1 -- 1.8L, Acura engine, 170hp

Thanks in advance.
- John