It seems to me that, if we first make it an algebra problem, we should be able to solve this relatively easily. If needed, here is a review of your secondary ed algebra RE: linear equations: http://www.purplemath.com/modules/solvelin.htm

SP=sell price = unknown variable x
CM=commission=0.1*SP
CP=supplier's price/cost = given
PF=Paypall fees =0.2+.0.34*SP
TP=total profit = SP-CM-CP-PF = 8

Substitute appropriately into TP function:

TP=8=x-0.1*x- 30 - (0.2+0.034*x)

If your algebra is good, this should be a relatively simple equation to solve for x. If needed, review the tutorial. If you get stuck, explain where in the algebra you are stuck, and we'll help you out.

Once the equation is solved for x, you should be able to put that formula into the "sell price" column to get what you want.