40$ is a pretty standard price. How long is diagonally from its right front leg (not pedipalp) to the left lower leg stretched out?
For sexing, 1 inch is pretty small, but if you get a good molt or a good ventral shot i can try. Try to get it so that it looks like this pic:
Make sure it is clear and well lighted, and i will give it a shot. That is a female btw. Ventral sexing is unreliable though, molts are more conclusive.
When you get a molt, try to open it up like this:
If the molt is fresh, it is a lot easier to open the molt up, you can use toothpics or something finer. If the molt has been there a while and is brittle, you will need to moisten it. Tarantula exoskeletons and water do not go together well because of the water tension, droplets will form (check this cool thing out, you can observe it if they have a food on top of the water in their bowl. If they are pushing on it lightly, you will see the water bend around their foot). A way to bypss the water tension is to put a drop of dish soap in a small bowl of water, mix them, and dip the molt in it. It will become pliable and you can work on getting it open.
For a female, you are looking for the spermathecae, which is where she holds the male's sperm until she lays her eggs. On a B. smithi (Mexican Red Knee), a female spermathecae looks like this:
However, males have special glands called epiandrous fusillae, which are there for spinning silk that is used for making sperm webs. It can make it confusing, as is shown here on a male B. albopilosum
Anyways, about the species. Chromatopelma cyaneopubescens (GBB) is not really aggresive, but it is very nervous and an extremely good and enthusiastic eater. They can be held, but it is not recommended because of their nervousness, and they are speedy. It will do just fine at room temperature like most tarantula species, and like EVERY species (even arboreals, i have seen them use them) they require a water bowl but other than that, its cage should be bone dry. They need a hide, but other than that, no decoration is needed. They are absolutely profuse webbers and will make plenty of decorations for themselves. GBBs are one of those halfies that can be arboreal or terrestrial. Most of the time they are terrestrial, but some seem to prefer the arboreal lifestyle.
Rosies are dirt cheap, and for a sub adult, 20 is a little more expensive then are usually found. I just thought i would mention that if it turns out to be male, consider selling it instead of doing a 50/50. You generally will not find people to buy them, and so you will have to feed a bunch of tiny mouths for years and years. A lot of people like to do rosies as a first breeding, and for a lot of people dealing in tarantulas, mature male roseas are not common. A lot of tarantula people do not like rosie and have none, as they are prone to strange behavior, mood swings, fasts, and they grow at an excruciatingly slow rate. There are a lot of mature males out there, but they are mostly in the hands of novices who are not going to breed them. However, as i mentioned before, a lot of people like to breed them for a first time and they they are many times willing to buy for the chance to have experience rearing a sac.