Check the Equipment Exchange on ar15.com for two-stage trigger groups. If you can find one cheap (under $100) buy it. Otherwise, Rock River regular trigger groups run about $25. Installation isn't shouldn't be a big deal.
The Romanian serises of AK Clones is no different than many other AKs of other Origin, Trigger group parts from many other AK series of rifles should be found and substituted, what is your SAR-3 doing or Not doing, than makes you believe it's the trigger group? If you tell us that or Gop to AK-47.COM I'm sure we can recommend parts to swop out, if you get US parts as well, it helps your legality in many states? Let us know OK? I bet we can Help ya?
SAR-3s are a unique breed of AK. Your best bet may be Red Star. As you get more into using the rifle, if you experience problems with the magazines, it may be that you do hot have Weiger mags. They are probably the only .223 mags that work reliably with the SAR-3. Century International and Copes Distributing sold Weiger mags at one time but the mags are getting hard to find and cost about double what a standard 7.62X39 mag costs.