PXSelector with where condition

This is how it would be written in F-bql:

[PXSelector(typeof(SearchFor<BAccount.bAccountID>.
    In<SelectFrom<BAccount>.
        Where<*your_conditions*>>), 
    typeof(BAccount.acctCD), 
    typeof(BAccount.acctName), 
    SubstituteKey = typeof(BAccount.acctCD), 
    DescriptionField = typeof(BAccount.acctName))]

However, if you’re looking for Vendors, it would be better to query from the Vendor table directly, as not all BAccounts will be Vendors, obviously.

Acumatica also provides some selector attributes out of the box which would probably save you some time writing a selector yourself, for instance [VendorRaw] or [VendorActive].