I always get my power supplies from
Allied Electronics, great service and I usually get the item within 48 hours of ordering. I've also ordered from
Newark but the service was a bit slower and the cost a bit higher than Allied Electronics. Either way, both of those companies sell the same items. A quick glance at the links mentioned above show that they sell the power supplies from the same manufacturers that Allied Electronics and Newark use.
My question though is what on Earth uses 13 VDC? I've used quite a few AC to DC converters for various projects and I've never seen anything want 13 VDC. Common voltages in the power supplies are 5, 9, 12, 24, or 48 VDC. Although I've seen some unusual ones now and then (almost all under 5 VDC). Can you get by with 12 VDC? If so there are tons of options that will be quite inexpensive. I saw with a quick glance just a couple of true 13 VDC power supples (minimum $100), and some variable ones (minimum $200). You'd probably be better off in that case getting a standard one over 13 VDC and using a resistor to drop you down to 13 VDC.
Other things to consider:
1) How much DC current do you need? The higher the current the more costly it will be. If the power supply doesn't list the current, you can be sure it is very low (many of those familiar blocky wall adapters fit this category).
2) How fast do you need the proper 13 VDC? A switching power supply is lightweight, small, and can use virtually any AC input, but can take 1-2 sec to reach the proper voltage. A linear power supply is bulky, heavy, and more limited on AC but they get you the proper DC voltage quite fast.