Piffle. Wheel truing is something anyone with the intelligence to ride a bike can do. You are the rider of the machine; it behooves you to know how it works and by that virtue, to know when something is amiss.
Wheel truing is tedious in the extreme, but it isn't difficult. A little imagination and time is all it takes.

And yes, you can true the wheel on the frame. Having the right tool for any job is the ideal, and a wheel truing stand makes the work go smoother. This is especially so for the rear wheel, because of all the shift gear back there. But it can be done on the frame with only minor inconvenience.
Of course you will need to firmly block or clamp the frame off the ground at a convenient height for working. Visit www.instructables.com and search for bike stands - there are a lot of impromptu and alternative work stand designs presented there for you to consider. Andnearly allof them are NO-or-low cost.
(You'll find a couple of wheel truing stands there, too.)

Not to sound indelicate, but before our society became awash in throw away income, we actually did things ourselves. Its only in recent times that we have come to believe we must give our money to others - to do the things we should be doing for ourselves.