314a ??

We check our customer data base and our wire log against the 314 a list, do we need to be checking other items like monetary instruments?

Yes, you must check those monetary instruments that are required to to be recorded, that is from $3000 - $10,000. However, you are not required to check against the payees on the monetary instruments.
Check the BSA Exam Manual for additional information on search requirements. There are also some FAQs out there regarding 314a. You can simply google for the FAQs.

Does that still hold true if we only sell MI to our customers? and never for cash.

As the 314(a) query process is relatively secret, we voluntarily refrain from discussing the specifics here. There is a detailed Q & A on the secure web site that answers your questions very clearly.