Ok well you have clear goals that makes a good starting point. Thou I'd caution against being in too big a rush and say, While It may well have possibly been me that said could be done within a month this would be for a equipped and experienced person having knowledge of what exactly required. Expect for it to take longer before fully working with any kinks worked out.!!

I will gladly help with advice and design ideas along with recommending suppliers but from the start I'll say I can't offer any more than that.? By that I mean I haven't got spare time enough to offer a design that is complete enough for you to follow has a plan.!
When I looked at the pricing and whether or not it could be done for the same money has Ebay 6040 then I worked from my experience and the little details I didn't need to know for pricing but when it comes to building a complete machine these details regard build strategy become very very important.

It can be done and done far far better for approx same money but a clear design plan will be needed.! I will gladly help you come to this design but mostly you'll have to do the work and really for the best chance of success and to make it an enjoyable experience it's very much in your best interest to fully understand the intimate workings.

I will PM you my number has I can help and explain far easier over the phone where has writing these lengthy posts takes lots of time which would only take minutes over the phone (Well maybe several lengthier calls . Lol). I know this doesn't help the others on the forum but it does if you start a build thread and pass on the experience which after all will be more directly related to this size machine and therefore more helpful to others.