This has always been a challenge for QRP operators. We know we can span the globe with a Japanese transceiver, a linear, a beam and a tower all costing thousands, but what may be done for the cost of a coffee in town?
There are many answers to this. It usually involves some element of compromise (usually with the receiver), but time and again people have shown that really simple gear works. I guess the "holy grail" is the rig that has the fewest compromises, yet gives you plenty of contacts. I am still looking!
One of the rigs I have tried is the Micro80 and the Pixie. A few years ago (possibly still) 40m Pixie kits could be bought with airmail from China for a few pounds. I have built versions for 80m and 40m and they have all worked. Albeit, the RX was far from perfect but they worked and resulted in QSOs.
The circuit is a typical Pixie.
See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/8040m-pixie-and-micro80-transceivers .