Hey Jim
The Echelon decals are waterslide and from what I know about Lawrence Goh through friends and direct communication I know he puts in a lot of research into his decals with his contacts. If you troll around Armorama you can find plenty of discussion where he's aided in questions or inquired about colors or markings to improve upon his products.
I find his prices quirte reasonable given the fact that typically he'll provide several tank specific decal sets, plus a large selection of generic number and letters depending on the subject. Shipping is included in his prices through his Spearheads Frontier website:
http://home.pacific.net.sg/~kriegsketten/So if you think about an average set costing about $12-16 USD which will provide you with 2-3 to potentially 10 or larger (depending on how big the generic sets are, and subject matter) different vehicle markings it's well worth it. Some of his smaller sets are as low as $6USD. For example, let's say you purchase a Challenger 2 Op Telic set, are you going to build all 6-8 tank specific models as per the decal set? Maybe, maybe not... but the generics you can use on any future project.
The photo reference that comes with the sets are great for placement and well researched.
These are my own comments and I welcome other people who have used them to contribute, otherwise... I imagine Lawrence himself will post to your inquiry.
Cheers Jim!!