Some purchases have been invaluable and some have been utter disasters.
In the "I couldn't live without" column:-
Sewslip quilting mat - so much cheaper than the Supreme Slider, this Teflon mat means I'm not fighting with my quilt quite as much as I would have been otherwise. I got mine from Quilt Direct.
Aurifil and Isacord for piecing and quilting respectively. Thousands of colours are available but I usually piece with 2024 from Aurifil (from Quilt Direct or Sew and Quilt)and quilt with white or block Isacord (from Barnyarns).
My small ironing pad and travel iron - they fit perfectly next to my sewing machine and mean that I don't have to keep going up and down stairs to press fabric. I can't for the life of my remember who I bought it from but I got it at the Festival of Quilts last year.
In the "Er, it seemed a good idea at the time" column:
Hand quilting hoop - I tried, I failed. I'm far too impatient and clumsy to hand quilt and am awe and inspired by those who do.
1/4" foot with fixed metal guide - I found it more difficult to sew with the guide as I couldn't see exactly where the edge of my fabric was. I now use a clear plastic 1/4" foot without a guide.
Cheap scissors - you definitely get what you pay for with scissor and I didn't pay much for these so...
Have you ever anything you regret? Or now wonder how you lived without?
Finally have you seen Katarina Roccella's new "Recollection" line for Art Gallery Fabrics? How gorgeous is this range?