Yes, depending on the mark-up. The problem is how do you know the true value of the import from a foreign seller, whereas you know for sure the selling price.
You are missing the point here.
The value of an Import is the same whether its a UK importer or not.
HMRC are not stupid, if they see an under declared item, they amend the price and possibly fine the importer for under declaration. This is an even playing field for all importers.
ALL imported products are subject to the FULL VAT and IMPORT DUTY payable, irrespective of whether you are a UK or non UK business.
ONLY HMRC can police VAT regulations.
This is not for ebay or Amazon, or any other global selling platform to do.
As an aside, if I was a non UK business looking to sell in the UK, I log on to the following HMRC sites regarding VAT:
https://www.gov.uk/vat-businesses/how-vat-works
https://www.gov.uk/vat-businesses/when-not-to-charge-vat
https://www.gov.uk/vat-what-to-do-if-youre-an-overseas-business-selling-goods-in-the-uk
The last link was published in July 2014.
Fraud is classed as a deliberate deception.
I don't think you can reasonably accuse someone of fraud in this situation. The onus is for HMRC to notify any offending parties and ensure they do what is correct. If after notifying the parties, they fail to adhere to any requirements, then the option is there for HMRC to prosecute.
It may be that a large number of non UK businesses maybe opting to employ a representative agent or are in the process of opening a UK company.
You do not know this.
I imagine that any business that has a large turnover and a successful business will play ball rather than risk not being able to trade.
Nobody knows what the profit margin is for any business and I suspect that any large business in China can legally trade and undercut any foreign business due to their huge advantage of buying and shipping much more cheaply, as well as the most important factor . . . . .They are prepared to work on a lower profit margin to get the business.
However much you scream, shout and cry foul, you cannot compete with Chinese volume sellers on price alone.
You must be able to provide a service(s) which puts you at an advantage by being in the UK and that UK buyers can appreciate.
You say you have a niche product. If it is manufactured generally in China, it will not stay a niche product for ever.
You must look at added services that you can promote where price is not the only factor or consideration that UK ebay buyers look at when deciding who to buy from.
I understand that the vast majority of ebay buyers are looking for the cheapest price possible, but this may change, as fair trade has manged to change people's stances when buying certain products.
Every business must adapt to competition, fair or otherwise.
Your assumption that VAT regulations, enforcement or fines will change the prices that Chinese businesses charge, will not happen.
I wish you good luck with your business.