depending on what you think you are gonna weld,I would almost say buy a mig welder.....now if it's purely motorcycle welding,yes tig would be nice,but do you master tig..
mig welders are a little more versatile but to get one you can really work with you will need to spend some cash...
I bought a "cheap" mig welder....known brand but their cheap line..spend $ 700.... didn't take me long to buy a "real" welder....a little over $3000 BUT now I got a welder I can do something with .....
honestly,cheap doesn't really work out for welders.......