If you are using the current bottom bracket and cranks, you will want to put the chain ring on the inside of the spider to get a good chain line. You may not have enough clearance to put the large chain ring there. If you are planning to ditch the other chainring, you will need new single speed bolts as well.
The prices for the wheels sound reasonable, assuming they are not using junk parts, but you can get cheaper setups online through the mail. Remember to add in the price of tires, tubes, cog, and lockring to your wheel budget.
Your chain rings will be for 3/32 chain, if you use this, make sure to get a 3/32 cog. You can use a 1/8 chain with either 1/8 or 3/32 cogs and chain rings, so that might be a more versatile solution.
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