I would like to know if a married person can buy real estate with out having their spouse signing the contracts?

Yes, you can buy real estate without the other spouse signing. But only if you are paying cash (no mortgage). If you are thinking of buying separately so in case the marriage ends in divorce, and are thinking the other party won't get half... you are wrong. Any real estae acquired during a marriage that last at least 3 months, the split is 50/50 even if the other doesn't sign.

If one is using it's own money to buy a property , would a Prenuptial Agreement avoid the spouse from getting 50/50?