There's almost nothing you can buy on Evike that you can't buy from continental Europe or Asia - It's cheaper to look east for purchases the majority of the time. USPS have a bad reputation for things of great expense never arriving in the UK when they come from across the Atlantic. I frankly trust EMS and others more than I do them.
Unless you want some of those knock-off PDI designs that Angel Custom make do some deeper Googling. Evike have good SEO and pop up frequently at the top, but that absolutely doesn't mean they're the cheapest or have the biggest range. UNCompany and DENTrinityshop are great examples of sites that never come up in search results but stock things almost no other retailer does. Same goes for European websites - most aren't natively in English so Google doesn't show them nearly as high as American websites, so you need to be savvy and get onto the 7th and 8th pages quite often to find the good stuff.
Also using Google advanced search tools, looking up product IDs and part numbers (rather than what you think the name is). It's all experience, but I can assure you that buying from the US is almost always a dumb idea (especially when they're producing close to 0 of this stuff themselves anyway).