The slabbed '34 I had wasn't slabbed by me. I don't think I'd go to the risk of sending valuable coins to the USA to get them slabbed, unless they were American or Canadian coins (which do go a bit mad when slabbed as very high grades). I've done it with Canadian coins before, and it's not that cheap really and only worth doing for the coins that you consider to be practically perfect. I sent 6 coins and 4 came back MS60+, 2 of which were MS64 and the other 2 were AU58. Most British coins still sell within the UK, and while it may be worthwhile doing it with the almost legendary modern coins, eg a top grade 1934 crown, a 1937 Sovereign, 1905 halfcrown, 1869 penny (all have to be UNC or better) etc...I'd personally not consider it for coins under £500 value, and I don't think the values of most coins would be increased all that much by slabbing. When sending things from the UK, the maximum insured value to the USA is only £500 and even that's touch and go if when something goes missing the RM decide it was 'money' and don't cover it! The best thing to do (and I have considered this) is save up a few top grade rare valuable coins (worth say £10,000 minimum to make it worthwhile) and visit one of the coin shows in the US where they grade them while you wait. Having say 10 coins authenticated, each worth about £1000 each to start with may well make them more interesting enough to cover your air fair. But....they are strict at PCGS/NGC etc, and you should bear in mind, that all the coins need to turn out at least MS63 to give them that extra something. No one will pay much over catalogue for most MS60's or below, and certainly most AU58's and below aren't worth slabbing.