Is there a web service where you can buy a large number with certain length? Not a Mersenne prime, but just a number and/or a prime? It needs to comply with th

Is there a web service where you can buy a large number with certain length? Not a Mersenne prime, but just a number and/or a prime? It needs to comply with the 2^n-1 formula. Let's say I want a number long 100 000 000 or even 1 000 000 000 long. Or a prime above that length. Do you know how much would that cost per number prime and non-prime?