The range and variety of interests within amateur radio is quite large, enough so that in a local club there may be a number of members each with their own unique interests, but as it has been a global hobby for over a century, there is large community of amateurs how may share an common sub-interest as yourself.
Two "sub-interests" that spring to mind are the QRP (low power) groups and members, including the QRP-L and qrp-l.org mailing lists, Northern California QRP Club, G-QRP club, and numerous others including Ashhar Farhan VU2ESE, who became a mini-celebrity with his BitX20 (affordable home made 20/40 meter dual band SSB transceiver). There are also numerous clubs and small to medium businesses selling QRP oriented kits. Because of the simplicity of not having large and complex power amplifiers, they often design and build simple CW (Morse code encoded on a C-ontinuous W-ave signal) transceivers, or even separate transmitter and receiver pairs. Many affordable (and a few not so affordable) QRP kits are available.
The other major area is in microwave frequency operation, as less amateur oriented equipment is available, so many adapt surplus commercial equipment or build their own gear to operate above 1GHz.
A few "big" references for amateur radio building are:
Keep an eye out for used copies of the ARRL or RSGB Handbooks, either one makes a great technical (RF oriented) reference about many aspects in ham radio including learning electronics and building things.
Informally, I find that UK and Indian hams are more likely to build some or all of their equipment than US/Canadian hams. So they tend to have affordable approaches to getting on their air, and operating.
If you have a decent understanding of basic electronics (i.e. the basics of diodes, transistors, ICs, digital logic) then the EMRFD is an excellent starting point, which starts off in chapter 1 with a couple of simple and small projects to start with.
Another interesting reference is the ARRL published book and column in their monthly magazine, QST, both by Ward Silver. The latter is for members only. The book chapters, or magazine columns form a series of very short treatment of a single topic, typically 1-4 pages with a simple and quick experiment or two.