Hi All,
I've been on the forum a few times in the last year looking for advise on painting foamies. I've learned less is definitely more when it comes to painting in the first place but for those interested, the best stuff I've been able to come up with is a paint called LIQUITEX. Its a spary paint but is a waterbased palstic paint. It takes a little getting used to for spraying but is clean and tidy and gets the job done well. They have a huge range of colours to boot.
A 400ml can costs 10 Euro in Inspiring Ideas in Blanchardstown, they are a great shop and know a load about painting materials like EPP. The cans may seem expensive but when compared to the RC Modelling Paints from shop, you'll pay 10 euros for 150ml.
Anyway I hope this may help.