As far as lengths go you have a couple of options, one is to buy some and cut it yourself, or look up the 80/20 distributors in your area on their site, and they will cut 1010 profile for $1.95. (price per cut varies with profile).
80/20 also sells the 1010 profile in 48", 72", 97" and 145" lengths direct. 80/20 also has an official vendor on ebay and you can buy it from them precut to size. The 80/20 price list indicates 1010 profile at $0.23 per inch for custom lengths. I found a fab shop near me through 80/20 that is a distributor and the they can cut and tap the stuff.
Fastening Options and Joining Plates are the two catalog sections that have what you are after.
You can also download the PDF price list after filling out some info.
What are you trying to do with the 90 degree angle?
For 90 degrees with 1010 profile you have few options, see pg. 155 in 80/20's fractional T-slotted Aluminum Profiles catalog section.
The stuff is not cheap though, here are some examples from their 2011 price list.
2 Hole Inside Corner Bracket
4176, pg. 274, $2.90
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3 Hole Inside Corner Bracket
4119, pg. 269, $3.85
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2 Hole Inside Gusset Corner Bracket
4132, pg. 288, $3.95
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4 Hole Inside Gusset Corner Bracket
4136, pg. 288, $5.65
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This is the catalog link you want, choose Fractional, you can download the individual sections or the whole thing (around 450 pages)
http://www.8020.net/Product-Catalog.asp
This is their eBay store front link:
http://stores.ebay.com/8020-Inc-Garage-Sale
EDIT Distributor lookup:
http://www.8020.net/PostalLookup.asp
You seem to be pretty active on ISR as well, there is a user there by the name of
nicka117 that periodically has full rigs for sale, and I think he was behind the rig design that 80/20 sells on their ebay store. Anyway he is probably the go-to-guy if you have in-depth question about parts and design. He has been very helpful to me.
PM me, if you want.
