djepudd: What do you buy first if you have around 120- 150 credits?
Easy answer is, "Not much."
More helpful would be to point out that free credits are plentiful. A check of your profile tells me that you belong to a CC with some very good players. It's been my experience that my fellow members have provided excellent advice. Seek counsel there.
You've made it pretty far with the basics. Yep. Time to upgrade, but it won't be cheap.