The above all good advice!
Man-O-Man I long for the day I can afford a cobra class 4 machine, the only way to meet any kind of cost effective production time. however I have yet to see a sewing machine that can make a double loop lace or a mexican basket weave. you mentioned you was not overly fond of border lacing but you will have customers who will want their projects laced so you might want to take the time to learn the double loop and mexican basket weave
with that said you can produce a nice saddle stitch in the same time frame as lacing up a project.
Stick with simple projects like the ones you mentioned unlined belts, guitar straps, holsters, sheathes, phone cases, bill folds, bible covers focus on leather goods that do not require massive amounts of sewing until you can work up the funds to invest in a good machine
a double shoulder of8-9 OX Veg tan leather will render several belts, guitar straps, holsters and knife sheathes.
items like billfolds will require a light weight veg tan.
Springfield Leather is a good supplier for leather and tools.
get a wholesale membership for a bigger savings
I would also mention I have seen some very good quality leather working tools coming out of Japan for several years now
Keyoshin Elle i think is the name brand.
I have also seen that Tandy is making an effort to making their Crafttool line better quality and
CSosborne is always going to be a quality tool.