Here is the best place hands down for what you want. It's hit and miss but a great resource anyways especially if you ever get into welding . Take a drive down to the local STEEL FAB SHOP. The guys who have the huge hollow building with the massive doors and the huge horizontal lift going across inside. You daily see semi's parked there with loads of flat and angle steel there unloading.
These guys do nothing but cut steel off 20' and longer runs of stock all day long to send to local contractors. They generate a few hundred lbs of scrap and cut offs every single day at least. It sits over by the ancient monster band saw and when they save the longer pieces on the side and pitch everything else in the 55 gallon barrel then when full it goes in the dumpster outside. I'm talking 1/8" at thinnest mild steel and usually up to 3/8". A lot of it is flat stock and the rest is either angle L shaped or I beam as well as thin and thick walled pipe up to around 5 or 6". You never know when you might need some of that pipe too for other projects.
You can almost surely find something that you can use. At most you won't spend over 10 bucks and likely they will just give you a few pieces if thats all you want. Just remember it's hit or miss according to what builders have ordered the last couple days.
All you need to do then is get a regular drill, steel bit and a block of 2x4. Put the plate on it, step on it and drill. No need for any drill press or even a starter punch. Get ya some el cheapo S hooks at the Chinese Tool store stick some cheap chain through and bang the ends shut with a hammer, paint and done.
The other alternative is the scrap yard. They got it but if you don't have a chop saw or torch to cut it it's usually not worth the hassle. It is a good resource if you do start making a lot of them later on . As with The steel fabricator shop the good old boy places will treat you better.
