Advice for a larger tripple-extruder reprap needed

Hello,
I am currently considering building a reprap that will give me a larger build volume and possibly multiple Materials.
Most importent would be a tripple extruder to combine two Materials and additionally print with water-soluble material.
And this is where the troubles start. Most boards will provide up to five stepper drivers, for six I would need something like the Megatronics.
Is there a way with Arduino mega and RAMPS?
Unfortunately I am kind of on a low budget for this project and seen a lot of affordable 5 stepper driver solutions on ebay.

I would not mind kits or partial kits either if it is less of an hassle then DIY and still affordable, and I do not have a large selection of tools (no mill, no CNC).
I do have a Printrbot, a UP, helped buid a Mendel, and I volunteer at a school, teaching Kids about 3D printing.
So I can print my own parts and I do have a little experience with Reprap, Basic electronic skills and I Know what a 3D printer does ;-)

The other subject would be printer size. Currently I can print 13 to 15 cm cubed, and my fiancee and I would like to print a starship enterprise lamp (aprox. 100cm length) for our living room. While she is for the NX-01 I am a great TNG fan, we have some time to build the printer before we will come to an agreement ;-)
The new printer should be large enough so we won't have to print dozens of segments.
I would love to have a 1m^3 reprap, but I suppose speed and stability will become an issue.
What rerpap variant is the best for a larger, multi-extruder design?
Above 25cm^3 would be an realistic aim, 50cm^3 would be great.
I am not looking for the fastest prints nor do I need the highest precision out there, for that I have the UP for now and another project idea for the future.

Also does anyone have experience with the extruder sets offered at eBay? There are complete extruders (stepper, fan, hot- and coldend assembled) and dual extruders for 50/115€.
I would build everything from scratch to save a bit, but not if just a few cents more would get me there half-way.

Sorry for the long post, to sum it up:
-What reprap design for a larger printer?
-Affordable, scalable electronics for 6 stepper drivers?
-oppinions on Kits or pre assembled parts?
-Experience with larger repraps regarding stability?

Thanks in advance, have a nice day! :-)
-Marcus

Building a large printer has a whole other set of problems need quite a bit of power in the motors going to need an enclosure and everything has to be extremely rigid I would suggest not using unsupported linear bearings and rods and using linear rails and bearings. This is going to get expensive and depending on how big you make it extremely wide belts or possibly very high lead ballscrews strength is very important once it gets to be larger

You could look at RepRapPro's Tricolour Mendel.

Hello John,
yes, I have seen the Tricolour, but hoped to either end up a little cheaper or at least a larger build volume.
Hello CNC Dick, thanks for the insight. Do you know of any documented larger reprap build that would be a good read?

Hello again :-)
Thank you for the replies so far.

I looked at a few cheap kits as in my experience sourcing parts here (germany) ends up more expensive then planned after several trips to the hardware- and electronic store when you "need just one more part" for a project.

Does anyone here have any experience with the Heacent-Kits (3DP02 / Prusa Mendel) from Aliexpress (for example from Heacent or "Darren Zhang's store" with positive reviews, or a similar machines as one from "YINKE")? I don't know if links to such discount offers are appreciated on this forum.
I have found a few posts on the reprap-forum regarding the Heacent kits available from Dealextreme and some info on their extruders. There seem to be some quality issues regarding the printed parts, but at around 300 Euro / 400 Dollar (shipped, plus import-duties and tax) it still seems like a good basis to source parts and build another machine, even if I have to re-print a few parts... As I would have to modify the design anyway, the mediocre plastic parts would be tolerable.

Axtheb on IRC told me it is a Prusa i2 design, so I have been looking for other sets, though none seem as cheap. As I just need something simple without high precision or speed requirements I suppose it'll do, alternatively I was considering building a Wallace anyway after seeing a 240x290x240mm on Thingiverse built by Mateusz, perhaps adding some frame parts for stability.

It's a bit smaller then I had planned on, but for my project but I suppose I should tackle one problem at a time, and I could just split prints if all else fails.

I want to order a dual extruder (66€) kit and another Melzi-Board (29€) to run as slave.
Seems like using two Melzi boards is a relatively inexpensive solution, and if I read correctly, it's what the Tricolour uses as well.

Thanks,
-Marcus