Tone's right... you need one of each
lol
You already have the makes for a great Amiga experience though with your A4000. What's the real problem, no RGB monitor? Finding one of them to hook to it is going to be your cheapest (if you can find one locally) bet.
The 3000 is great for what it is and for cosmetic reasons, is my favorite modern Amiga as well. It can be a major hassle tracking down systems sometimes and re-installing software, etc. Personally, I'd just build on your A4000 by getting an Indivision AGA card and go from there. You won't regret it (unless you start to experience the bad capacitor syndrome so many seem to these days).
