All depends how much you can get in your area, and how much you want to earn. The simple approach is to multiply the cost with a factor - others differ and come up with quite elaborate formulas for pricing. The blank cost $25 plus a nice kit (I used the black Chrome click Sierra for $10), so you out already $35. Since you live in England, you have to figure shipping to you cost in, plus some finishing cost (sand paper, mm and the like) as well as cost for tooling (bushing, mandrel, gouge, skew etc). So, make this $40. Use a multiplier of 2 makes it $80 for sale, use factor 3 and you come to $120 sales price. I personally do not think I could get the $120 for it in my area, which is normally a high price area (NJ, close to NYC).
Its all up to you - and as I said, I use this simple approach.
You can do a search and you find a lot of pricing info here on IAP.