Not at all; this is by design. Cain is supposed to charge a lot, and it should be a while before you're decked out in rares, uniques, and set pieces.
If you want to acquire some rares on the cheap, get some low quality items imbued by Charsi. You're bound to end up with something decent after a few tries.
Also, you can "reroll" rares that aren't useful by using the cube recipes in the "Item Recreation" section of the Cube Recipes page
in the documentation. Hang onto the reagents and jewels you find.
Lastly, consider using previous characters to share items with newer characters, by taking advantage of the shared stash. You only have to fight tooth-and-nail to collect decent equipment once--it gets progressively easier.