I bought a old-ish Dell E4310 from Craigslist for about $200, then spent some more $$ to dump a 500GB SSD to store the full PSDZ data and ISTA files. Something like
this and
this.
If you're going to flash your ECUs, you're going to need a ICOM unit as I dont think you can do it over ENET. You're also going to need a external power source to power all the ECUs while programming. This is done using a specialized programming charger or having a second running car connected via jumper cables.