If you'd like to play with a fully worked-out scheme of the sort you mention, try this:
http://www.gamesdiner.com/rules-nugg...er-cost-for-st
In short, it uses a clever pricing scheme (credit as noted; not my invention!) that keeps normal GURPS ST scores and effects unchanged, but reduces costs at higher levels so that every 50 points multiplies BL by about 2. Every 300 points multiplies ST by exactly 10, and BL by exactly 100.
Benefits:
- With this sort of logarithmic effect, costs down in the human range are unaffected, but the cost of Superman-level strength is vastly reduced.
- It works for both supers and just plain big creatures - and actually makes pricing the latter simple. Spending 50 points on ST per +1 SM yields realistic ST (to be further adjusted if you like, of course).
- With this scheme, there should be no need for GURPS' SM-based cost adjustment to ST, meaning that small complication can be dropped.
Drawbacks:
- Unavoidably, a varying cost for ST means figuring final cost will take a few more seconds than a nice, simple 10 pts/+1!
Anyway. I don't claim it's what you're looking for, but you might find it interesting.