If you do any meaningful amount of buying and selling you can't really go by the amount of money your shop has taken in. I mean, mine is at 400m and I can't say I've ever had an account worth over 30m.
But then again, I have a huge gambling problem, so YMMV. yum_pie
I'm really enjoying the newer items. I am turning over my inventory I think. I'm kind of glad the rigs go down so fast, that means I can wait to buy them. I'm used to the mindset of all items being worth more over time. What an outdated gaian economic though XD