My absolute must haves for quilting, besides a good sewing machine, are
(1) a good ironing board and iron. You can buy a cheaper iron and expect to replace it or get one with a good guaranty. I don't use steam, preferring to spritz my fabric with either water or spray starch, so purchased the Continental iron from Amazon. It doesn't have any holes in the sole plate, which is great if you are doing a lot of fusibles.
(2) Serrated blade scissors. I love the Karen Kay Buckley scissors, but Kai, Havel and Gingher also make serrated blade scissors. I won't ever use non serrated blades ever again! Not only do the serrations act as tiny pinking shears, the serrations grab the fabric and pull it into the blades, rather than pushing it away as smooth blades do.
(3) A good cutting mat and rotary cutter. Get a rotary cutter that is comfortable in your hand. I have 4 different brands, but love my ergonomic Fiskars.
(4) Long, thin, sharp pins. Clover makes some that are 1-7/8" long with glass heads (so you can iron over them); flower head pins are nice to have because you can mark letters and numbers on them with a Sharpie; and Karen Kay Buckley has some very thin, very sharp pins. The only drawback with them is that the heads are so small.
(5) A June Tailor Shape Cut; a 6-1/2" square and a 12-1/2" square.
(6) A good light so that there are no shadows around your presser foot.
(7) A good seam ripper (or two or three, because they seem to wander off at the most inopportune times). I like the Clover seam ripper with the white handle, because the point seems sharper and finer on those than any others I've used. The Clover brown flat handled seam ripper is also good.
(8) Good needles -- Schmetz, Superior Threads, Organ. You can also buy Bernina, Janome, etc., but those are made by another company, and I've found they're no better than Schmetz and cost more.
(9) Good thread. I buy Prescencia (sp?) 60/3 weight, 100% cotton thread by the cone. I get mine from Harriett Hargrave's website, though I am sure there are other places you can get it. Also, it comes in a 50/3, but I prefer the 60/3.