Yes, there is a site called POE trade. You can search there for what you would like and then when you find something you want to purchase, there is a button which says copy to clipboard. You click that then control v it into the chat window in game and it will message the guy (or girl) something along the lines of "Hi, I would like to purchase your megasword of instadeath for 1 chaos in Harbinger". They then should send you an invite, accept it, get to town, push s and right click their name and goto their hideout to do the trade.
Be warned though mate, low cost items or stuff that has just been posted are prone to people not answering. Usually if you message someone who has literally posted something they ignore it, then you see the same item later but for more cost. It might be an idea to enable 'person is online' when you enter the criteria for what you are searching.
1 tip I will give you though, is try to spend as little as you can levelling up. Don't waste Jewellers or Chromes on gear you're going to out level very quickly. If you need the slots or colours for them to fit gems in, make sure you REALLY need said gem first. it's usually better to wait to be able to equip the gem. If you find you are coming to a halt in progress, maybe buy a weapon for like 1 chaos or so but leave it at that if you can and just use what you find on the way. Also!!! In act 3, there is a place you can go to called the Library and in there there is an npc called Siosa. Do his quest and then you will be able to buy all gems from him, this will save you having to make a mule if you can wait for the gem equip.
Hope this helps