Because some varieties are not self-fertile, if planning to have a
single tree then be sure to get a variety that is self-fertile.
However, even self-fertile varieties usually bear more fruit if a
second variety is available to exchange pollen.
In a pinch, you might cruise around the neighborhood looking for
another peach tree flowering at the same time, and beg a branch from
the owner. Take the branch home and use it to pollinate your tree.
I have a single pear tree (legacy from a previous owner) that needs
this treatment. I don't know what variety it is, so buying another
pear from a catalog is chancy; I could easily end up with one that
does not bloom at the same time as the one I have. What I probably
should do is beg a cutting from another pear in the area that does
flower at the same time.