Wheel Issue KX250

I have a 2004 KX250 (2 stroke). The wheels are straight, and good, however, the spoke nipples are seized, and not adjustable.

I recieved the bike this way, and intended to ride until I had an issue with it. No issue yet, but am thinking of getting black rims.

I have heard some companys will let you send in your hubs, and lace up new rims. Has anyone ever done this? Is it reasonable? I dont need top flight rims, as I am an old Vet D class rider who only rides 2 or 3 times a year.

Have seen complete sets as low as $500.00 on eBay etc... But have no issue with my stock hubs.

Prefer not to go hunting for prices at wheel co.'s, would like input from you guys.

Thanks for any info.