Since Saving Pvt. Ryan came out, genuine 1903A4s have been snapped up by collectors. Even those miserable Weaver 330 scopes are getting expensive (last show was $300). You can build your own, but the cost is destroying a pristine M1903A3.
BTW, the best buy on sniper rifles right now are the Russian Mosin Nagant 91/30s. Expect them to go up once War of the Rats gets released.
On the side, I believe the best sniper rifle of WW II is the British No 4 (T). It was very rugged, accurate and its optics, while heavy, was very durable and well sealed. The Springfield had a cheap Weaver scope which fogged up, leaked and had to have its lens removed to drain the tube. The M1C was a good gun, but came out too late and being semiautomatic, was not as accurate as the No 4(T). The Germans (per Law) could never get the right ammunition (irregular performance) for their Mauser 98 rifle and many of their Sharpshooter rifles had that LER 1.5 X scope. They had better scope, which they used, but by far the second best gun would be the Mosin Nagant Sniper (especially if the Finns rebarrelled it). Like the No 4(T), it was also very durable and accurate. Less we forget, that NVA sniper also zapped Gunny Hathcock with one.