Thread is not cheap. Keep your eyes open for sales. If you buy online, check to see if the shipping is cheaper if you buy more than one spool of thread. Some sites will charge the same shipping no matter how many spools you buy, or free shipping. Because there aren't any shops around that I can go and see the threads and colors, I buy a thread charts that have actual little patches of thread so that you can see the real color. They are not cheap... maybe $15. So if you find a brand that you like, it is worthwhile purchase in the long run.
When starting out, decide if you want to use polyester or rayon thread. Poylester will not fade if bleached, while rayon can. Some of the rayons stand up better to bleach nowadays. Some like rayons because of the lucious colors. But now some brands of the poly threads are looking as lucious as the rayons! You can use both types in the same design witihout a problem. As others have said, just buy a spool of a brand to see how it works on your machine. When you find a brand that you are happy with, get a set of it. Some thread collections are only 500 yds and therefor cheaper. A one hundred spool set will probably meet your needs. Sounds like a lot, but once you start stitching, you'll need a color palette to choose from. Use the color chart to see which colors you would like to add to your collection. The more thread that is on the spool, the cheaper the per yard cost is lower. You might think that you'll never use 1000yds of a thread, but when you find yourself using a particular color...like a Christmas red that I use tons of...buy a bigger spool of it.
When you buy bobbin thread, buy a 10,000yd spool. Yes, I didn't think I'd use that much either, but it'll last a long time. I use only white and black unless the backside is going to show. Then I put embroidery thread in the bobbin too. Some people use serger thread in the bobbin. It is very linty, but will do if you run out of bobbin thread. Just make sure you clean the bobbin area out frequently.
Metallic threads are notorious for being finicky, but you gotta love them. King Star is the only brand that I've found to be trouble free on my machine.
A lot of people don't like Sulky threads, but my machine and I love them. You can buy them in small amounts at your local Joann's store. They are starting to carry larger size spools, but sometimes I just need one particular color and it is convenient to go to Joann's. I watch for their sales, or use coupons to buy threads there.
http://www.allstitch.net/department/...mber-10075.cfm for Maderia rayon&poly
http://www.allthreads.com/colorcard.aspx for Robinson Anton threads, sample of color chart rayon&poly
http://www.isacordthread.com/categor...ery_Thread/c88 poly only
http://www.embstore.com/p-1561-kings...ter-cones.aspx for metallic threads
http://www.uncommonthread.com/Sulky-...Rayon-s/42.htm can be purchased at Joann's