From what I can find about Kraftco they are pretty scammy. I went to their web site and it has zero information. I couldn't even find a site for USCrafts. You should not have to pay people to work for them.
Generally, assembly-type jobs are not legit. I've read countless people getting involved with those and are promised a certain pay once the project is complete to their satisfaction, yet it never meets the criteria... therefore no pay. But, they make money off you. There are plenty of jobs out there. Stay clear of those!