First, have you kept inverts before?

Brazillian White Knee is generally A. geniculata. It's a fairly good beginner species, I wouldn't consider it handleable though. It's a very good eater and pretty hardy. It gets pretty big, to about 8 inches from leg to leg.

As for scorpions, the classic P. imperator, a desert hairy scorpion or a flat rock is a good beginner. Desert hairy scorpions are either H. spadix or H. arizonensis.

Be sure to buy from a invert dealer and NOT A PET STORE. Pet stores often mislabel the inverts and they are overpriced. Pet stores are particularly bad when it comes to labeling the scorpions correctly, and sometimes very hot scorpions are mislabled as species which are not very hot, so be warned.

A couple of the invert dealers are www.botarby8s.com, www.swiftinverts.com are two of the good ones. There are several others, but those are a couple. I've delt with Botar personally. Most of the major invert dealers go to shows, but I don't know what area of the country you're in, or I could give you more specific dealers to look for.

I can post my entire list of beginner species if you like.