I myself have a pastel and a 100% het albino. I'm not sure on the value of snakes in your area but my pastel was £250 (but I got her for £175 as they had a deal on that day) and I got my het for £70 from a private seller.

I think the best thing to do is to go to a specialised reptile place and have your brother look through the morphs and handle a few in his price range to see which he prefers, this is what I did with my pastel although my budget was considerably lower first going in to the store. I think handling will help him decide as I think personality and how tame the snake is trumps the morph (personal opinion).

There are so many morphs available! As you can see from the link below the list is endless!
http://www.worldofballpythons.com/morphs/

I wish you and your brother luck in finding the perfect ball python and look forward to hearing the results!