My games are always 3 way, one player each faction and between 100 and 200 points,hence the size.
Crappy piece of wood - free
20 * A4 fridge magnet sheets - £17.95
Various glues - £5
Quite pleased with the result. We tend to drink while playing, so "space quakes" are not infrequent. Needs a glue cleanup and some kind of paint job. Still experimenting with the right size of rare earth magnets for ship bases. Next up asteroids/debris.
Would recommend to other players wanting a cheap board set up.