I know I may be a bit late. I did not check personally but I believe you should find Parker metering valves at PETROTECH ESTABLISHMENT ( http://www.petrotech.ae/store.html#
I researched this a few months ago and only found this on the internet. I did find one store that had a vast amount of metering/needle valves in Shuwaikh at near Bin Nikhy garage (the "German car brand" street) however I did not check carefully since none had a box. I just had my Co2 tank checked today a ROC. However my acetylene regulator does not work with Co2 as I have found out. I assume the Victor brand regulator was at Roc. I do not think you will find another regulator but you may get lucky at the Friday market. I think an inert gas regulator should work with Co2 but the dude at ROC said you should get a Co2 regulator only. You could try building your own regulator but anything other than restaurants is extremely difficult to locate.
If you want an alternative carbon source, I have found and purchased Sklarcide (3% glutaraladehyde) which is the same stuff as Flourish Excel (would be more than happy to share with you) . I also have found sources for a lot of things after A LOT of time (fertilizers). If you need any help just send me a pm, I'll be more than glad to help. (unlike the other Kuwaiti which changed his location in his profile after I sent a pm)