Your husband will be happy once he opens this gift. Although if you can offer some more information about him it might be easier to answer. How long has he been modeling for, does he have any experience with resin casting, and how big are the parts he is replicating? Without making it obvious any more info would help us out more.
But with what you have mentioned, i would go with an alumilite. As its the main resin, and rtv silicone i use. If its his first test trial. This starter set would be nice.
http://www.alumilite.com/ProdDetail....tegory=Starter Kits&Name=Mini Casting Kit
Same, but a larger set.
http://www.alumilite.com/ProdDetail....tegory=Starter Kits&Name=Super Casting Kit
And if hes asking for a big setup buy them individually. BTW I've always had good experience with alumlite. And do remember they have a shelf life. Hope this helped at least a bit.