Based on your "mV" question, I'm going to assume you mean strain guage type load cells for weighing applications.
I've had good luck with Sensotec over the years, and I know Omega Engineering has them, but they of course are usually higher priced for a small volume user. Have you searched the Thomas Register site?
Quite a few PLCs haveI/O cards that can take the mV signal directly, and in many cases thermocouple (T/C) cards can be configured to take a linear mV signal. The AutomationDirect.com PLCs, for ecample, have this kind of module in a number of models.
Are you sure you want to do this, though? mV signals are incredibly susceptible to noise, and unless the PLC is in very close proximity to the load cell, or you are in an incredibly benign environment, you will not get a clean signal and will be fighting inncaccuracies for the rest of the machine's life. It can quite often be very, very expensive to save money with cheap components.