Hi,
I'm a bit of a vintage singer sewing machine collector and the rolls royce of singers for leather is the 201 and you can pick them up in uk for a song. Absolute works of art and often set in beautiful oak and cast tables. Look on gumtree for your area or ebay, they go for under 100 pounds. The earlier ones were cast iron and weigh a lot but the post 50 models were alluminium i believe for lightness. Perhaps the earlier ones would be more suited for heavy duty work, look on youtube for vids of these machines sewing leather.
wow, so happpy i've found a thread to offer some advice on on this site!