Can I sell items to test the market before informing HMRC?

[isimology]

I don't wish to commit to registering as a self-employed business with HMRC until I've validated the market for a new product.
Would it be ok to place 10 prototype items I manufactured myself onto eBay with a private sellers account?
In testing my marketing concept, these products would carry my own unregistered trademark brand name.
Personally I wouldn't consider that a pattern of trading for profit but I don't want to give eBay, PayPal or HMRC the hump.
Any thoughts?
Mick

(BTW I would offer customers a no quibble returns policy.)

 

[Billmccallum]

call it market research, should be fine.