Depends on the level of quality and which model you are referring to overall.
Range varies between, $800-8000, which on the high end is a full blown restoration with a NOS playfield, plastics, parts, and complete cabinet restencil.
The low end is a function game, but has severe cosmetic issues on the playfield, cabinet, and backglass.
It is possible to go into the $400-500 dollar range, but it is going to need a lot work, and electronics are going to need repair, and probably is incomplete.
This is also normally a EBD LE model.
Keep in mind, the extreme end of the sales, is very rare and stupid...
I have even seen a couple of original 1981 games go HIGHER than that (close to $10K), but somebody must have REALLY wanted that game. Absolutely ridiculous.
I recently was offered an insane amount of money from a potential buyer on my fully repainted and colored EBD "Classic" that I built from a wired playfield.
The game is not for sale, but I may bring it to a show in the future, if I decide to bring it out of storage.
See the EBD owner thread for consideration of other details regarding the different versions and prices, if you want to "get in the groove".
I still remember when 1981 EBDs was stacked 10X high (cabinets offset back and forth horizontally) in warehouses, just waiting for a "rainy day restorations" by brokers.
I need to find that photo, it was a forklift ballet dance, and dangerous, but the games were stacked up against other games.
It always has amazed me that the original Eight Ball is not as well liked (today...), because it has nearly the same level of quality in terms of shot challenge, and nearly equal in artwork for plastics and backglass.
A fully restored EB (Bally, 1977) version with a NOS playfield, backglass, and re stenciled cabinet averages between $2000-3000.
Playfield swap outs are expensive to do (between $1000-2000), even though this game is rather simple in comparison to most late model games.
A nice example will run around $1000-1200, and it is solid state...