Try looking in long arm university. A woman in Vancouver is selling an hq16. I think that may work for you.

Most of my quilts are queen or king size and I do most of my quilting on my domestic Viking Sapphire. I love it.

king size on a regular machine
 

I quilted a king size quilt on my regular machine. the design was split rail and I made the quilt top in 3 sections. then I put my backing and batting together with each section and quilted each part separately. after each section was quilted I sewed the sections together. I took a class in quilting this was at the LQS. And I think there is a book available on quilting this way, actually listing 2-3 different ways to join the sections.

I have quilted many quilts on my DM. I baste the dickens out of it, start in the middle and work my way outwards. I have made at least 3 twin size, several double, and several queens. A job, but it can be done. I use 2 ironing boards with plywood boards on them--one in front of the machine and 1 to the left of the machine. I don't wind up with wrinkles, etc. My recipients like what I do.

Quilt as you Go
 

The quilt feels wonderful and looks great. I loved the fact that I could stash them quickly in the car (or by my chair when at someone's house) when we stopped every three hours or overnight. Here are three pictures. I will do this technique again. Hope this helps

I do all my quilting on my regular sewing machine. I have a struggle with the bigger ones but it works out ok. I don't send anything out to be quilted by the ladies who have a long arm. I just can't afford it.

I have quilted 87 quilts on DSM, Most on a Juki TL98QE w/9" throat. It is a straght stitch only machine. I do a large stipple or meandering. No fancy stitches for me, I don't care for them. I wear rubber tipped garden gloves, start in the center, work out to the edges. No way would I have my quilts quilted, I like the fact that I make them all myself. I have done up to a queen, no need for a king.
I have made a few QAYG, otherwise I work with the whole quilt, never in sections. It is so easy to quilt after a few.

I have a long arm - but I have quilted even large quilts on my regular old Brother sewing machine from Walmart for years before hand! I bought my long arm mostly for myself but I do quilt for others to earn a little extra fabric money. But I also quilt - A LOT. Daily. LOL* So that's part of why I bought it. But if I weren't going to ever quilt for others I probably just would have bought an extended throat sit down machine. Those expensive toys are FUN but not necessary. You and do it! The more you sew the more you'll know what is right for YOU. ;)

Thank you! Pretty quilt!

I have quilted a few quilts on my Janome 6600 cot, single and what I think is called a twin in the USA, in the UK we call it a double. Again just meandering FmQ on the larger sizes but on the cot size I have started to be more adventurous. I think the most important part of quilting on a domestic sewing machine is making sure you have really sandwiched the quilt well and that there are no creases in that bottom layer......for me sewing the quilt altogether is the very best part....suddenly the quilt gest life and it changes from a caterpillar into a butterfly. I dream of a mid arm or a long arm but don't think I'll ever save enough to get one, but I also don't like the thought of someone else finishing what I have started so wouldn't ever send a quilt off to be done......but that is just a personal view as I know a lot of people do and they look amazing.