wood instead of coroplast?

I am/ was building a C&C cage. The problem was finding the coroplast at a decent price locally. I found a couple sign stores that sell it but for 15-22$ for a 4x8 sheet. I thought that was a little much considering in the closest city I can get it for 7.82 for the same size sheet. The problem is, I would go get it in the city, but they close at 5 everyday and I'd have to get my husband to go with me, and also borrow his parents van to get it home. He gets off work at 4pm and we'd never get there in time. So basically that option is out since I don't know anyone else to help me get it that has a vehicle big enough to get it home in.

So my father in law is really hand in his woodshop. He made us our cabinets and helped alot on our house when we built it. So he said he can make a bottom for my cage. I have the wire cube/frame done already, just needed the coroplast for the bottom tray. He measured and did a little diagram and said he can make one out of wood. Its going to be about 7.5 inches high on the two longs sides. I little higher on the two ends with a cut space up higher on those two ends for me to be able to lift the tray out if I need to. He's going to make it out of wood thats maybe 1/4 to 1/2 inch think. preferably 1/4. Also it WON"T be spray finished or anything, I told him not too, in case my guinea pig were to chew on the wood , the finish wouldn't hurt her. He'll sand it so its nice and smooth, no splinters.
he is even going to make a little hay trough to attach so I can put her hay in there. The only problem I can see and that I am worried about, is having a wooden bottom, won't her urine eventually , even with bedding in there to absorb it, soak into the wood cause either oder or the wood to start to rot or get nasty? What sort of thing could I use to line the bottom? Will just newspaper do or could I use some contact paper so that its easier to wipe up, then put news paper on top of that, then the bedding? Or could I use a piece of linoleum to line the bottom of the wood box, then the bedding? Or plexiglass? should I seal the corners with silicon? I am worried about urine or water soaking into the wood eventually. Also the other thing is will a wood box be dangerous at all in anyway? I think it will last longer definately, and it will be cheaper than the coroplast anyway, since he probably has all the wood in his shop already.
Let me know your ideas on this. I want to do it so that its safe, convenient and will last a good long time. It won't exactly be a C&C cage, but a C&W cage, (cube and wood instead of cube and coroplast!!) Would this work right?