The Pottery Barn Matine Toile Duvet cover is $149.00 for a Queen, and standard shams are $29 each. That's not terrible, but let's look at other options.
Here's another option for you, sew. I know, it's a scary option, but I promise the sewing machine won't bite. And here's some incentive for you; this option gives you the freedom to create exactly what you want for CHEAP!
For example, here are two brown toile fabrics I found on Fabric.com.
To make a queen sized duvet cover you'd need about 5 yards of fabric, and a flat sheet (which you may already have). At the fabric prices listed above, you could have your own toile duvet for $35-$50.
Tired of me beating you over the head? It's okay...You don't have to sew if you don't want to. Really, I won't make you...I'm not going to come to your house to check up on you. Just giving you options here :-).
Sheer, Flowy Curtains/Something to Hang them On:
The lovely Pottery Barn curtains surrounding the bed are $25-$30 each.
But what do you hang the curtains on if you don't have a canopy bed? How 'bout a ceiling mounted curtain rod? Like this one from JC Penney's?
Or, you could get super creative like this gal and build a wood frame on the ceiling and staple the curtains on the inside.
I would also scour Craigslist and fleamarkets for canopy beds that you could pick up for cheap.
The paint color used in the Pottery Barn room is Benjamin Moore Kona (AF-165). It is really dark, though, so only go this dark if your room gets a ton of natural light. Also, I wouldn't recommend picking a paint color until you actually have your bedding since you want to make sure the browns match. I know...I'm being ultra helpful here :-).
So Let's Price Things Out:
The Pottery Barn Room: Bedding $207; Sheers (4) $100; Bed $1,299
Our Super Creative Option: Bedding $39-79; Sheers $10-40; Ceiling Mounts for Sheers $20-60
And...that's how I shop. That's how super-tight-income-little-'ol-me can afford to beautify my home. I hope this exercise gives you some hope that you can too.