Hi Tom, welcome. Basically, it's very hard to cost anything that's a one off. I have people say Ooh I like that would you make me one, the answer is I'm afraid, you couldn't afford it. Now, in terms of anything mass market that get churned out by the hundred, the costs of course are much lower. But one offs? Nah. There is so much time making these things as you go along with no drawing, now measurements and so forth, it's like a handmade suit. I've made several wheel carriers and there's considerable work in them and no two have ever been the same. That being said we will ALWAYS help some one out on here if we can. It's why we're here.
Where abouts in the country are you. That's the place to start.