Copper tacks. Oak board. Pre-drill. Don't need standoffs.
I've used this method for a few fixtures like my OT impedance checker. works real well except I prefer Baltic birch plywood, Oak is HARD and brass soft, I have a heavy had even with a tack hammer

so I bend them in oak a lot.
I'm a cobbler and scrounger by nature and I've found the cheapest way to make a good board is the way Leo did, fiber board and brass grommets.
You can find fiberboard in a lot of different places. I've bought an old suitcase from Goodwill for $3 and it was lined with the stuff. most fabric stores have brass grommets in the scrap booking section that are small enough. I recently have used Arimid gasket material I bought at a local machinery salvage store.
In general I have to say, buying some board and a couple hundred turrets from Doug is by far the best and easiest way to go.
in the grand scheme of things you can save the most money buy using salvaged tranny's. PT OT and choke usually end up being about a third of total cost. Speakers are the next big chunk and can be another third. so a Cab, chassis, tolex, faceplate, pots, hardware, caps, resistors, wire, sockets and tubes together cost the remaining third.
So if you've got some iron and a speaker your more than half way home.
THE CHEAPEST BUILD
Find an old organ. Craigs list, Goodwill, Salvation Army are the usual hunting ground. PLEASE don't dismantle old tone wheel hammonds for parts. all else are fair game in my book.
You'll still want to buy new filter caps and resistors for reliability.
LOL I noticed I was saying YOU a lot, I don't mean to come off like I'm ordering you around, what I mean to say is I do things this way and have had good success in building a few frugal amps.
Ray