For those on a limited budget, what's the consensus on using Creatine Select vs. Muscle Synergy? I would probably only be able to use one of the two products--which one would be the preferred product to use if I had to pick one?

I truly believe that Muscle Synergy is the superior muscle and strength building formulation, not to mention it being one of the first NO products on the market. If you are going to use Synergy, you must take the full dose to get the full results. For a male 200lbs or less 16 per day, over 200 should take 24 per day.
Creatine Select is a great product as well, and is a little more cost effective. Although it does not have the NO benefit, it does contain Beta Alanine which buffers lactic acid and increases exercise performance. Combine this with added strength and you'll be able to pack on the muscle.
Either way, you can't go wrong.
CR