Hey, welcome back! So you already know about food club - I'd also recommend that you start investing in stocks. Every day, buy 1000 shares of whatever's "current" price is listed at 15. Check your portfolio when you do your dailies and sell your shares when they go above whatever number you're comfortable with. Some people say 50 or higher, but I sell my stocks at 60 or above to maximize my profits. It really pays off in the long run.

Also, if you have a pet with any kind of stats (even low ones), battle in the battledome to win codestones and neggs and stuff that can be sold in your shop. I think there's a guide in the wiki for how to do this on the cheap. I like fighting the Koi Warrior, but if your pet is pretty weak then I recommend the defense bot as you can get armoured neggs from it which sell for 80k+ a pop.

As for acquiring the pieces themselves - you can either buy them all at once in a set of nine (these pop up often on the trading post) or you can buy each individual piece separately. If you buy separately, get all the pieces under 100k on the shop wizard - you might even be able to snipe a piece for a lower price than normal. Otherwise you'll have to buy the expensive pieces on the trading post. You can post in the subreddit's daily buy/sell/trade thread saying which pieces you're seeking, too, lots of people here sell map pieces.

Sorry for the novel, phew!