@Sleephead1 I guess it all depends on the child. Some will love the rainbow, others may not take to it. I really don’t think 4 is too old for a child that way inclined though. You could print off a load of medium difficulty builds and different ball run set ups from Google images and give them to him for inspiration. Children do generally need a bit of guidance, initially at least. Any builds which require the semi-circles, rather than shell out more money, just make them from strong card.
Unfortunately Grimm’s products are very rarely reduced and certainly not the rainbows. Demand usually outweighs supply as they are handmade and desirable. Grimm’s simply cannot always keep up with order volumes, hence the decent resale value. If you find your little boy really doesn’t take to the rainbow, you could always sell it on eBay/Gumtree and you’ll probably get most of your money back.
If you do go ahead and purchase, I wouldn’t recommend buying from Amazon, they usually (but not always, so do check) charge more than independent retailers. However, independents don’t always have them in stock, but most have a stock alert facility so you can be notified once they have them again.
Independents also usually offer 10% discount, to name a few:
www.babipur.co.uk (10% off discount code is dewi. They change the code every few weeks, I think this code will therefore shortly expire)
www.yesbebe.co.uk (10% discount code is babble, you get sent a 15% discount code with every order)
www.consciouscraft.uk (10% off when you sign up to their mailing list)
www.littleacornstomightyoaks.co.uk (10% discount code is unicorn poop)
www.littleearthfarm.org (10% discount code is lovegrimms. They currently have a 15% off Grimm’s promotion with the discount code hello, but it expires at midnight tonight)
www.mymummystoycompany.co.uk (10% discount code is tenoff)
Don’t order from Baba Me, I’ve only ever heard bad things.