Read the reviews. This toy is made of "Sensofirm" (a "2" out of 10 safety ratings. That is probably the reason it is out of stock and will probably stay out of stock.) Sensofirm is not a healthy or safe material, based on the fact that it is very porous and is an anal toy! Bacteria can get trapped in the pores of the toy and cause health problems. There are better anal toys out there.
Go through the silicone anal toys and read the reviews if you are interested in this kind of toy. There are literally dozens, if not hundreds of healthy anal toys that have been reviewed by Eden reviewers.
Click on the name of the toy on the product page and it will say "read reviews." Go to the reviews, read the highest rated ones first and they will tell you just about everything you want to know about the toy.
Eden has over 50,000 products, so reading the reviews is the best way to find out what you need.
#1: Get silicone. They'll last forever, are easy to take care of, and are safe.
#2: Don't worry about a kit. Play around a bit with fingers, figure out about what size you like, and get some really good toys a la carte. If you're interested in "training" then get two (one at a known comfortable size, one a bit bigger), then make the next decision when you're ready to move up.