As it has turned out, the myStorm people came out with a board called the Black Ice, and are now shipping the Black Ice II for £42. It has a 4k Lattice chip as well as 16 bit wide SRAM, and the open source tools are able to use the whole chip capacity, making it an 8k Lattice chip.
https://www.tindie.com/products/Folknology/blackice-ii/

Lawrie, a friendly commenter over on the MyStorm (BlackIce) forum has just posted a long list of dev boards which use Lattice's icestorm-friendly FPGAs:
https://forum.mystorm.uk/t/rival-to-bac ... /5?u=biged

I haven't checked them all out but would expect them to be very affordable.

(icestorm being the open source FPGA software which targets Lattice iCE40 devices)

Found another (recent at time of posting) list of FPGA dev boards:
https://joelw.id.au/FPGA/CheapFPGADevelopmentBoards

via https://hackaday.com/2018/08/20/cheap-f ... d-roundup/

It's 2022, time has passed, and there are widespread supply chain problems.

So the price and availability of FPGA dev boards will have changed... what do we see today which is attractive, for features or price?

I note that one of our number has bought one of these, or something like it:
Sipeed Tang Nano 9K FPGA Development Board
It uses an FPGA from GOWIN, which has its own proprietary toolchain, but it doesn't sound too bad. And there are lots of resources on-board. And just possibly the open source apicula project will sooner or later support this chip. (The page I link mentions RISC-V but that is, I think, just a suggestion. It's an FPGA dev board, with lots of RAM, and various connectors.)

(Commentary on personal reasons for not liking some particular chip or vendor are not going to be particularly helpful here, I think. Let's share notes on things we do like, and refrain from commenting on things we don't.)

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Yes, no objection to reasoned criticism of course!

The Tang Nano 9K is worth picking up for anyone who wants to play with FPGAs; it's pretty powerful for the price. The software requires you to apply for a free license, which they hand out like candy, but just plan to get hounded by sales guys for a month afterward. My only real complaint is that the documentation is still a work in progress so you're going to be relying mostly on the example projects posted on GitHub.

(I should also point out that the Linux version of the software, like pretty much every vendor IDE I've used, takes some coaxing to get working on any even vaguely recent Linux distro.)

My personal favorite of the boards I've used is the TinyFPGA BX. It's about $40 and uses the fully open source IceStorm toolchain. They have decent resources, though I wish they had more available I/O pins. Still I managed to cram a decent CRTC into one including a 6502 bus interface.

For something beefier, the ULX3S is really nice, but we're talking about a big jump in price range (I think I paid about $150 for mine). For that price you get an order of magnitude more resources (both LUTs and I/O pins) and some useful built-in hardware like SDRAM and an HDMI-compatible port. It uses the Trellis toolchain, which is also open source, and shares a lot of its tooling with IceStorm.

In an ideal world I'd suggest the TinyFPGA as it's better supported and documented, but I don't think you'll find them in stock anywhere right now. In fact the Nano is probably the only thing not backordered these days.