CSP: What do you mean by telling us to find you a DMR rifle? First off, AMR stands for Designated Marksman Rifle, so there is no DMR rifle.
- In my definition a DMR is a semi automatic AEG, that is within the normal allowed fps for full-auto capable AEG-s (so you have no MED), but has it's accuracy improved all the way.
- In the US Airsoft rules definition a DMR is a semi automatic AEG, that can shoot faster than your normal full auto capable one, but has an MED.
Either way, the DMR is not a sniping tool, it is ONLY an accuratized AEG. Get any full-metal quality AEG, replace the tight-bore and bucking (maybe the chamber), reshim, relube and get a good battery. There, you have your DMR.
Word of advice: External modifications WILL be quite expensive, so forget those. As for the internal ones: A DMR level tightbore will usually start around $60-$80, the bucking is cheap ($20 or less), but the tweaking required to get a consistent fps is incredible. A simple accuracy upgrade (tight-bore, bucking, chamber, nub) may cost you upwards of $150 if you intend to buy the best quality. And those parts are usually not straight drop-in upgrades, usually they need a lot of fiddling-around to work properly. Also, in airsoft DMR-s need fps consistency. This means you need to have a perfect compression - more tweaking, and more DIY modding.
From what I understand after spending months and nearly $1000 on building my DMR this is not a "recommend me a good one out of the box", as there is no such category. If you look at the sniper's perch, there is a thread called cost of a Sniper/DM (I do not remember) rifle. The price tags will get you on the ground, as the usual one is around $5-600. OK, this is for a Bolt Action Sniper Rifle - but I would not expect to pay less for an AEG DMR.
I will give you some basic points on where to start looking:
- ICS sportlines or airsoft GI's G4 series can be a good starting point if you intend to upgrade a high(er)-end AEG. Unfortunately for you, really high-end AEG-s that would be ideal for your goal are above $400 not counting any upgrades or accessories. This also means, that you may be spending an additional $150+ on a metal receiver in the future.
- If you want to go the ACM route: Get any AEG you like, throw out all the internals, spend $4-600 on the new internals. Then, spend $100 on a scope only to find out that you are unsatisfied with your externals and spend an additional $4-600 on new externals. Oh, so it WILL cost you $900+ ? Sorry, that's the price of a DMR.
- If you do not have this amount of money I suggest you forget the DMR route. Get an AEG (any quality ACM replica will do), and replace the tight-bore with a Madbull one. Replace the bucking+nub too. This should provide you with a relatively accurate platform for around $250. Then, you can swap out parts one by one. This is the slow way, and it will take at least a year to have your DMR.
From another point of view there are two AEG-s that come into my mind when building a DMR as a base gun:
The Cyma 032 M14 (or M14 Socom), and the D-BOYS/Kalash full steel AK-s. Both are relatively good out of the box. AK-s and M14-s also have hop-chamber designs that are in the top 3 for airsoft, so even the clones are quite accurate out of the box. The Version 3 and Version 7 Gearbox shells are quite strong and durable compared to a Version 2 (M4 line), so you will get more high-powered shots out of your gearbox before the shell snaps in two.
There is an AEG upgrade guide in the AEG section, I would recommend browsing through it (yes, all 30+ pages starting from the first post). It will take you days, but will answer most of your questions.