There are many companies that make industrial power supplies capable of 12V and 7A, or way more--such as Meanwell, PULS, or Lambda, to name a few. These are available in enclosed, open frame, DIN mount, and other form factors. Whether or not you consider them affordable is something only you can answer--for ~100W you're looking at probably in the $20-60 ballpark.
Mouser, Digikey, and other similar electronics suppliers will have these listed in a nice searchable form. For DIN rail format supplies, you may have better luck at an automation supplier.
You could use a very simple arrangement of components to make your own power supply--all you need is a transformer, a few diodes to make a bridge rectifier, and some capacitors to smooth the output, however to get 12V and 7A out of such a simple power supply will not be very efficient or demonstrate very good regulation--and it will be very heavy due to the large transformer required. For better efficiency, you'd need a switching power supply, which is decidedly NOT a simple arrangement of components, particularly if you care about safety, reliability, or EMC.