My wife and I bought our thank you cards from Optimalprint. They were nearly the cheapest option and came with envelopes that are self sealing.
The card quality is high. They are about postcard weight.
The print is accurate and the gloss finish does indeed show the image off well.
The packaging was secure and they were well organised into batches inside (we had three different cards).
All in all very good and very easy.
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