Tailoring a 36 to fit a 34?

No. Buy suits in your size. Don't assume just because you save a lot on something initially the work meant to make it look normal is justified. Plus, when dealing with tailored wares, it is almost guaranteed you will fail if you try to make something it is not.

Get the proper size. Getting a jacket majorly altered costs a lot. It would be cheaper to buy one that fits at regular price than to buy one on sale and have major work done.

If you're looking at H&M suits, the tailor bill will most likely more than the cost of the suit itself.

The most critical measurement is the width from shoulder to shoulder, the rest can usually be adjusted if it isn't too far off. Depending on your build you may be able to fit some 36s but you'll need to experiment and also try various brands as sizing is a bit all-over-the-place. A lot of the designer/european suits you'll see on Gilt, Yoox, etc tend to be slim so you may have luck with 36s if you aren't super narrow - and I've seen Yoox with 34s so there is that possibility too. If you know what shoulder width works for you then the B&S forum and even eBay can be a good source.

I'm usually a 36S(hort) but I also own a few 38S so don't focus solely on the listed size, try some on

 

If I may, which RTW dealer carries size 34 suits on inventory in the US?

1. no, this probably won't work. Partly because some elements can't reasonably be altered, and secondly becuase it's not just the size, it's the proportions and you definitely can't change those.
2. Here's what you need... READ - http://www.styleforum.net/t/68936/clothes-for-the-short-guy-stores-brands-lines-websites
3. Search the forum, there are a NUMBER of threads about size 34 suits and who makes them...