There is a lot of play in yards. I know 1 that is about like the welding store, small customers are really an interruption for the most part. In common sizes I buy by the full piece and some chop for free, if I can help it this is what I do and stock some common sizes, not a lot but a few ft of angle of various sizes around save a lot of work. Same for little rounds and flat strip.
There is another yard in a different town loves walk ins, prices decent and you pay stick price for drops but its really kind of nice as they got a decent selection and dont mind a look over, can buy a chunk of channel just what you might need without having to get a whole piece or a surcharge for a short. Same for plate.
If I really need to buy a 16 ga or really any plate unless it is a drop deal am taking the whole thing. Building a little stock is near priceless and when used with salvage can go a long way. I can do used on some things, where there are lots of welded attachments or prep is a problem, even finish then new.
Butttttt,,,,, most home brew types should really be looking at free and salvage, not all of it has to be welded, can be spot cleaned, screwed etc but appliance steel is the super source for free stuff, lots of it has pre bends can be useful. Its all cleaned and painted super easy to work with, some of it can be snip cut in places etc.
I got all the pieces for a welding booth, all of it from a washer dryer set and a can of flat black, even used the same screws come out of a lot of it and only a couple small pieces of additional matl that didn't come with it.
I added a shaded window and a flap or 2 since and need to make a minor wire change before my bucket time. The white hardhat is actually the motor cover, it fit so perfect we never made a real deal. I didn't buy anything for it, used both doors as the fan install is in the wash door up top, used dryer fan and dryer door incl old hinges for the cab.
There is a big ground wire not seen bolts to the plate the vise sets on which slides around for adjustment. It goes to the welder.