Best place to buy second hand books?

Hello!

At the risk of sounding like a auld cheap bastart(maybe I am) - can anyone recommend the best places to pick up second hand books that are decent condition and not ridiculously priced?

I work in town and used to go a wee walk to charity shop and pick up a couple then re-donate them after id read them but it feels charity shops aren't much cheaper than brand new nowadays.

I remember when I was much younger(maybe 15 years ago) there's was a great book shop near Oran mor but im rarely up that way so unsure if it still exists.

Ive also got a bundle I need to donate so if anyone knows of places needing book donations please let me know that too :) work in town but willing to go a wee adventure at the weekend to check other places out.

As always thanks in advance for any help.