First and foremost you'll need a darkhouse, spear, and method of holding a live decoy.
Portables work great for spearing. I mainly spear out of a hub-style pop-up. You can find them new for less than 200 bucks. Simple mods can be done to the box-style portables as well. Check craigslist for them and you can get em for less than 100 all day.
For spears, you can also find them on craigslist for as cheap as 25. A decent new spear is around 100, and real good one's can be had in the 200 range. Want to spend the big bucks? Pick up a custom Kraemer spear. They start at 500 and top out around 1200.
You don't need to go all out and buy fake decoys. Any baitshop will have a decoy "pin" for holding a live sucker, and you can rig it in your shanty any number of ways. I suggest you search around this forum. You'll find EVERYTHING you need, and I won't have to type a dictionary
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I guess you'll also need a way to make a hole. New spuds are around 70 bucks, but I highly recommend an ice saw. You'll find these new between 130 and 170.
All said and done, if you buy everything NEW and get good stuff, you're looking at between 500 and 600 bucks. Sounds expensive, but everything but the portable shanty will last your entire life, and the lives of your children, and grandchildren...