Hi doug,long time no speak,hope you're ok.

The best you can buy i guess is the lee system,which is very expensive ?133 for a set of nd grads. The quality is unquestionable though. Alternatively i use the cokin holder, which is about ?8 i think,plasic but it does the job, ?4 or ?5 for an adaptor ring. I then use the hi tech resin filters which are well thought of and i like them very much. Don't use the cokin neutral grad filters ,they are 'neutral grey' and not a true neutral grad,they will impart a colour cast. The hi tech are dyed right through the resin filters. I haven't used the lee so can't compare the two. Guess it depends on your budget.