Anyone got a decent size cheap laser engraver ?

Noticed that the price for the larger laser engraver kits has come right down recently.

I'm looking at an A3 (40cmx30cm) 500mw model. I have a 1000mw laser from my miniture engraver (just too small to be of any practical use - 38mm square just isn't pratical) that should just drop in.
https://www.ebay.co.uk/itm/DIY-Deskt...AAAOSwG1NafTw3
Is what I'm looking at.
Like that it's made of 2020 extrusion - used to attaching stuff to and modding that :-)
Also large enough to do place mats in one go and can be placed on anything larger if necessary.

Been skimming through various forums and some info - including a great page with links to just about all the software you might need.

So a couple of things I'm curious about.

Could you upgrade the controller board to something that could run off an sd card ? - given where I'll have to use it, standalone engraving would be very useful. Failing that I'll use an old netbook - got a couple around
Could you, For example, use an mks gen 1.5 board (as I've got one of those going spare).
Most engraver boards seem to run on grbl, so no idea if you could load that on the mks board.

I've got a feeling I'll need to join another forum. Life is too short lol
So thought I'd ask round here first :-)

Had some money in paypal from selling various 3d printed stuff - so in real terms only cost me £34.
No doubt the bastards at HMRC will rob me of another £20. But I have now ordered one :-)

I know that colorfabb's woodfill is great for engraving. So will be able to try engraving weird shaped things as well as flat stuff :-)

Coming from HK - so be a couple of weeks at least.
Time for me to tidy up the work bench and sort the netbook out. 128gb ssds are down to £34 at the moment so might drop one of those into the netbook. lol