I have been on a similar journey.
I have an old slow laptop which I use for Farming - I can plot on it - but it takes ~12hrs per plot - I occasionally use that to slowly fill up gaps on hard drives.
I started using my desktop PC to do faster plots - I have an SSD, but like you not enough memory to make a big enough RAM drive. I was getting 2.5 hr plots, which is good, but to jump to the next level I would have needed fast SSD drives and loads of memory - which costs loads of money - and would make you PC run really slow while plotting and will slowly wear out the SSD.
So I now have an old server in the garage - you can pick these up for ~200GBP on ebay for a server that can do plots in 1 hr. Now when ever I have some spare cash I buy a new hard drive - connect to the server - run it for a few days - turn off the server and move the disk to my farmer.
Servers are noisy and hot and expensive to run, but as I am only using for a few days a month it is fine.
The server in the garage is only running madmax - so I don’t have my Private keys anywhere near it.
This means my actual PC is always available for work/ games.
Obviously you need the room to have a server ideally away from you normal living space - but I am sure it is the budget option for cheap fast plotting - I have rambled on about the speeds here : Proliant DL380 g6 Server slow plotting - #24 by teeboy