Declaring $30 for 3 steelbooks is not out of the question. Custom won't know any better. You think they're experts at premium steelbook pricing? As matter of fact $30 for 3 steelbooks is way more believable than $200.
Customs can often know better and are more strict in some countries than others.
Customs can and do find out about Blufans prices been marked low and they often select premium retailers a different times during the year to keep tabs on the marked value on parcels arriving into country
They have targets to reach each month on parcels to be caught for VAT collection
It's just down to luck on the day with customs if they select your parcel to inspect you can go months even years and not be hit for VAT by customs and then all of a sudden have a run of parcels you get hit for VAT by Customs
A invoice is meant to be inside the parcel showing breakdown of price but most retailers who do mark price down on customs label won't provide the invoice inside the parcel as it makes a legal case against them easier to be processed
One Click's are more likely to get caught by customs in some EU countries simply due to
1)Parcel Size
2)Parcel weight
When they inspect as in open the parcel they first thing they look for is a printed invoice and also what the contents are
Customs are getting lot more wise to parcels from China and Korea having low marked prices in some EU countries and in some cases will simply ignore the marked price on customs label as in they don't believe the price been marked by the retailer
Some EU countries customs are very strict as in Germany
UK is less strict and just luck you not been caught out for VAT
Personal Parcels sent in the post is less likely as in very rare to be caught by Customs compared to Retailer Parcels
A retailer can refuse to mark the value low as it's actually illegal to mark value low and they risk been taken to court if caught.