I buy my collidal silica gel from the HFS. The cost you mentioned sounds right to me.
I also eat A LOT of silica, now. When I say A LOT, I mean I eat Cost Co. 1kg bags of fresh spinach like it's going out of style. (It's nothing for me to go through 4-6/week) I also eat a lot of green beans. Oats, if you can tolerate them, are a really good source. I eat a lot of greens, including watercress, swiss chard. I just find the vegetable sources easier to tummy versus the grain sources. The gel got me started and I still use it to supplement, but not at the level I started. It's more of a maintenance dose.
The silica stuff is in tons of skin lotions/hair products as well, incidentally.