For us, the crib mattress was never a problem because it had a waterproof surface that could easily be washed. Many, if not most, crib mattresses seem to have waterproof surfaces.
Finding a safe twin mattress when the time came (per the issues on solveeczema) was more of a challenge. Most mattresses are covered with fabric of some sort. Many mattresses are filled with potentially problematic materials. Even natural and organic bedding contained cottons and wools that were certainly washed along the way. Latex was a potential allergen in our case. Even if we did risk it with a “natural” mattress, the cost of most was prohibitive.
After much research and cost comparison, we ended up ordering a “No Compromise Organic Cotton Ultra – Twin” from Naturepedic Organic Cotton Twin Mattress. We ordered it directly from the manufacturer, who was able to match the usual free shipping deal everyone else was offering on the web.
The mattress cover is organic cotton, coated with a waterproof dust-mite barrier of food-grade polyethylene on top, sides, and bottom. It’s pretty inert. We have had no congestion, eczema, or other allergy issues with it. (Note: When it arrived, it had a slight smell – not significant compared to most mattresses – which was gone after a week or so. Not all of this manufacturer’s products are entirely covered by this barrier, this is the only one that seemed a pretty sure bet for us.)
We considered an inexpensive metal bed frame from Ikea, but at the time we were buying, they didn’t have a design we liked. It was tempting, though. They had one all-metal bed frame for under $40.
We ended up getting a solid maple bed frame from Pacific Rim. It had the option of no finish or an oil-based finish. We took a chance on the finish, and let it air out for a few weeks before using it. We have had no allergy issues with it either. (The model we chose also had fairly sharp corners – a problem for us in a very small room – so we simply sanded the corners. It wasn’t difficult, it looked fine, and we no longer had problems when we bumped into the frame.)
Prices for this same bed varied wildly on the web. We got the best price and terms from Satara Inc online store.
All told, the mattress and frame together were, for us, a big expenditure. However, the quality is great and they should last for decades. Having no allergy issues was priceless.