I would go for a DVD writer as it can also burn CD
I got a DVDRW from click here
OEM version for about £55 inc P&P
There are three (I think) writing formats DVD + DVD - and DVD Ram, so you need to decide which one you want.
Some of the newer drives also support dual layer disks and writing (more storage space) but are still quite expensive.
Most drives support + and - some support all three