Google +paradox +cheap - alternately +paradox +oem on the net. Otherwise go to a Robert Austin show in California (google it). The oem version is to be sold with a new computer. Once speaking to Paradox support I was told that not buying it with a computer was not illegal, but I'd take the somewhat cautious path and pick up a piece of equipment (ergo a new computer) you need like a hard drive from the same vendor. Student versions are also cheap, but somehow that really seems like cheating.
It is most unfortunate that Corel doesn't get wise and promote a free standing version of Paradox. Every time I mention database to colleagues, their eyes just glaze over. Trying to explain what the tool can do for you just leaves them believing you are either a genius, mad or both. It coule be such a seller.