There are ample reports of 10+ year old Ball Pythons breeding...
Black Pastel bred to a Pastel will result in a variety of appearances in the offspring. The odds will be: 25% Normal (Wild Type), 25% Pastel, 25% Black Pastel & 25% Pastel and Black Pastel.
For reference, a Pastel and Black Pastel specimen is commonly refered to as a Pewter. Pewters are very pretty snakes and are saught after by many hobbyists. They are my girlfriends favorite morph. A hatchling typically sells for around $500.
Breeding a Black Pastel to a Spider will result in the same as above, just replace "Pastel" with "Spider" in each percentage. Although I have never heard of a "Black Pastel Spider", so I cannot suggest what this will look like.
Hatchling pastels go for around $75 (inexpensive male) to $200 (expensive female). Prices on adults will vary greatly based on gender, size and appearance. An adult female (1,500+ grams) will go for around $400~500. Though a little more or a little less may be found.
Hatchling Spiders for for around $150 (inexpensive male) to $350 (expensive female). Prices on adults will vary based on gender, size, appearance and head wobble. It's uncommon to find breedable adult females, mostly because spider morphs are highly saught after and breeders snatch them up.
Also, be aware that Spiders come with "head wobble". This is a genetic retardation that appears to different degrees in all Spiders. Most breeders will boast that their Spiders do not have wobble, but most, if not all, breeders that say this are flat out lying.
I was at a reptile show a few weeks ago and had three different breeders assure me their Spiders do not wobble, yet while they were saying this their snake began to wobble in front of me.
I'm not trying to convince you not to go with a SPider, I'm just trying to ensure you know what you are getting into. Use google and you tube to get an idea of what I mean by "head wobble".
www.faunaclassifieds.com is a good place to shop for Ball Pythons... I bought 2 of my 3 from breeders who advertised there (the other was bought at a reptile show).