In addition to what RES says, you will need to figure how how to split the crankcases and reassemble them with conventional puller and presses. Most of stihl's tools can be worked around (except the flywheel puller which is reasonably priced) - I didn't have most of them for a long time... but I broke a couple of crank cases along the way...
Talk to your Stihl dealer. Maybe he will rent you the crankcase tools for a few hours, or, if you prep everything, pop them apart for a few $.
I never really bothered with Stihls bearing and oil seal insertion tools (quite inexpensive) but i did mess up a perfectly good $19.00 oil seal in my 088 instead of buying the $1.45 assembly sleeve! Now I have a nice set of the more common press tools and it was worth it.
What types of saws are you considering?