A rating 5 skillsoft (think 4ish) would cost 7500 nuyen and take up 75 Mp.
The skillwires system itself cost Total Mp x Max Rating x 500, so just to slot one rating 5 skillsoft it would cost 187500

A rating 3 system would run 40500 per every activesoft you wanted to have running at a time. And these weren't like today's modern activesofts, where you get to roll Attribute + Activesoft. No, you couldn't use your extra dice pools. You just rolled the Activesoft and that was that.
Realistically you could only have one or two softs running at a time before you were bankrupt.
In SR4 it looks like the cost of the system is very cheap, while they've made the softs very expensive.