Sorry for the novella to follow, but I know this subject. Definitely home dec fabric. Collars, cuffs and pockets are I believe cotton velvet or velveteen. Silk velvet has a bit of a sheen which is lacking in the photos. Your silk link is gorgeous, has an intense sheen and would certainly work with the lighter weight home decor fabrics. I just checked a length of my cotton velveteen and it would work well, nice drape for the collar.
What you need are sample books from a home decorator or interior design store. Locally most smaller upholstery places didn't have much in the way of sample books. Hunt around and ask around. Bergen is a big city, you should be able to get some.
Fabric styles and color trends change every year and the sample books get dated fairly quickly. Depending on the decorator/interior design shop, they pitch, give away or sell the swatch books. Some have long standing arrangements with people who make little one off decorative pillows that are sold in boutiques and these days on Etsy.
I got most of mine from the local quilt shop. BFF of one of the owners is a decorator who deals mostly high end and she would haul in boxes of the books about once a year. Bigger samples, about fat quarter size of heavy fabrics got turned into dog beds for charity and the rest was for the picking. Most quilters only saw what you could do with the cottons or dog bed suitable ones. I got the silks, sheers, linens, embroidered ones etc. I tried not to be greedy, but...
The swatch sizes vary widely, depending on type of fabric. The majority of the fancy brocades and embroidered ones are often 5"x 8" to 8"x 10". Velvets and piles are usually more fat quarter size. The books usually have 40 to 60 swatches and are either a full line, with a lot of colors or color ranges, with every fabric that comes in that color from that company in the book. The color ranges would be perfect for you. Most of the ones I have are fabrics that sell for US $30 to $65. Stuff I'd never buy yards of.
What I would do is get enough of the velvet for the main parts and extra to use in the garment of that dominate color to keep the theme solid. Then 1/4 yard pieces of maybe 3 other solid velvets. The samples are big enough for 3 or 4 smaller bits from small ones, more from the larger ones. You could always get 1/8 yard pieces of one or two brocades if you wanted a less scrappy effect. I'd go with the full scrappy effect the sample books would give you, as that is definitely in the spirit of the Shire.
Fiber contents will be all over the place, all sorts of blends, and either dry cleaning or spot cleaning of the finished item would be best. Some pieces with the look you want might be much lighter weight and a really light weight fusible interfacing might be good on those.
These fabrics tend to ravel a bit so overlock the finished seams.
Just this morning I was looking at some of my swatch books. Sorry postage would kill us or I'd share.