Does your husband by any chance remember how many mg of phe he was allowed as a child? Each person with PKU is different, so it is hard to say how much phe he can tolerate. In my personal experience before I began Kuvan I was allowed 300 mg of phe, which is approximentally 6 g of protein (50 mg of phe=about 1 g of protein). With Kuvan I am now allowed 900 mg of phe. On the other hand I know others who have PKU that are allowed much less than this, and others are allowed much more. It really does differ on an individual basis. His specialist may start him at what he was allowed when he was a child and the adjust it from there. The only way your husband will be able to figure out how much phenylalanine he is allowed is by restricting his diet, doing a blood test, and modifying his diet according to his levels. Treatment for PKU is a lot of guess and check.
As far as snacks go almost all kinds of fruit snacks (fruit roll ups, fruit by the foot etc) are ok. Hunts lemon pudding, most chips and popcorn in moderated amounts are ok, fruits are usually ok, most fruity candies as long as they are not sugar free/contain asparteme.
I personally love the low protein rice and pasta. I grew up eating the low protein rice and pasta, so naturally I am used to what it tastes like. Can I ask what state you live in? I am just asking, because I know some states do provide the metabolic formula and/or some staple foods such as pastas, rice, baking mixes, etc. Here in Wisconsin formula and foods such as pastas, rice, baking mix, peanut butter etc are provided through the state. As far as I know the wheat starch does need to be specially ordered. Here are some websites you may want to look into: cambrookefoods.com, myspecialdiet.com you can also purchase cook books and a phe book (which lists the amount of phe in a variety of foods) from this website, pkuperspectives.com, dietspec.com, dietforlife.com, and http://www.listserv.emory.edu/archives/pku-support-l.html this is a mailing group that thousands of people with PKU and their family members are a part of. If you would like to subscribe to it the third link down should read Join or leave the list (or change settings) click that and go from there.