I don't have a place around San Antonio that I've used but I highly recommend JM Bullion. Process is super easy and you'll pay the same premiums as you will at any of the places in town. I always wait for sales on coins/bars. They don't have a minimum quantity and you'll get the lowest premium even if you just buy 1. They have a $200 free shipping minimum but that's pretty easy to hit.
There is a Gold/Silver thread on the Business & Investing Forum that offers a lot of advice on types and quantities. If you need advice on how much premiums run then that thread will have them. The sales on JM bullion normally drop the premiums way down. Silver has a huge premium as a percentage of price so hitting the sales is great. Hope this helps.