welding should be learnt by any weightlifter powerlifter strong man.
if you want to save money this is the only way to go.
the items you have listed would be a piece of piss to make......but watch out for more complex machines (dont try and build any hammer strength machines!!!!)
I made a sled for a friend, a reverse hyper for home. weights plate trees.
I plan to make a lifting bench, weight releasers, and plenty more....just need the time