LoL. Dont use it for sales anymore really, although most prices are siimilar on Crom, with the exception of Sourmetal and Shards, Shards are dirt cheap over there compared to Set, also Crom doesnt seem to rip players off as much on Ibis / T3 crafted. Tin / Illustrium and such are similar last time i checked.
Buy/ craft some ibis / T3 before merge on crom, then sell right after merge for 2x before prices stabilize. Prices for shards should drop as there are a lot more farming / gathering on Crom. Then again that takes gold to earn gold. If you are starting... best bet would be to get into a shard farming instance and farm a couple.. sell right after merge as there will be Set players trying to buy all / raise prices.. which probibly will work short term, but due to amounts probibly wont long term