hmmmm getting VGA (RTG Graphics) on any Amiga is not going to be cheap I am afraid.
An A2000 is a modest start to be honest, to make the magic really happen you will need to spend money on it.
Fast DMA SCSI II + 8MB FAST RAM
this will give your 68000 8MB machine 2MB of RTG graphics - it wont be fast with a stock 68k moto though.
this will take your 1MB CHIP and upgrade it to 2MB chip, giving you 8MB FAST 2MB Chip.
from that you are looking at £150 - £200 investment on top of the cost of the A2k itself, and yet to get the most out of it you then need do some serious upgrades like the CPU
A2620@14Mhz or A2630@25Mhz
This will come with 2 or 4MB of FAST RAM, you will need to remove said amount of RAM from the GVP SCSI card
That will give you 8MB FAST, 2MB CHIP, 2MB RTG and it would be quite usable, going any further would be a dedication and labour of love.