If you have a quartz crystal ground for the 40m band, a QRP transmitter kit is very easy
using that. It means you can only transmit on that one frequency, but is the simplest
type of transmitter. (To change frequencies you plug in a different crystal.)
Here is my personal favorite (which can also be built for 80m):http://www.qsl.net/g3pto/pippin.html
(You can simplify it a bit further, but this is a good starting point.)
The issue then becomes the construction practices, and getting the parts to build it.
As the others suggested, I strongly recommend finding a technically knowledgeble local
ham to help you. They may have all the necessary parts in their junkbox (a generic term
for "electronic parts stash"), as well as being able to help with soldering, etc. (This
circuit could be built on a "solderless breadboard", or other types of construction.)
None of the parts, except the crystal, are expensive or difficult to find, and crystals are
available from various sources (including ham swap meets.) Crystal control isn't a bad
approach to start on 40m where much of the QRP activity is centered around 7030 or 7040.
Having a VFO will be useful at some point, but requires a bit more care to get a good