Pits are the Cats Meow... when the birds want to be in that specific spot.
Like many things, You can go as cheap or as expensive as your imagination can take you and because they are such a pain to put in, you only really put them where you know you'll have the spot for many years and more importantly... the ducks/geese will always be back. (in Illinois they are quite popular and some very extravagant... but really only on the club properties and long term lease fields next to refuges.)
I can tell you they are a lot of work to put in, but where you can use them it doesn't get much better. If I can find the pics, I'll post up some photos of one pit we placed out on a mud flat for geese and black ducks. the material was relatively inexpensive... buddy found a box we could use, real cheap/ free. (Love that word "Free") . Then he told me where he got it and what it was... Coffin Shippers! GASP!!
gave me the heebee geebees!!!
we had to bail it out at low tide everytime we wanted to use it and the Atlantic busted it all to heck by the end of the season, but it was fun while it lasted. We sure pounded the birds out of it!
Like the earlier posts, my suggestion for hunting MI would be to go with some of the great layout blinds that are now available (and now cheaper than ever before). Considering the quality of these new blind systems, their cost/portablity, the michigan season and our reduced bag, it's not worth putting in a pit anywhere here.