[3.5] Cheap DR

[Bauglir]

I'm currently building a Lockdown Fighter-type of build. Lots of reach, lots of AoOs, lots of tripping. But now that it's coming together, I've noticed that I don't have a lot of hit points (88 at level 10), no mechanism for reducing damage (using Swordsage instead of Crusader, for Step of the Wind instead of Thicket of Blades), and a terrible AC (20). So my current thought is to use my wealth to pick up some cheap, disposable DR, since the character is built for a potential oneshot and the authors actually priced AC boosts consistently, as a general rule.

Any suggestions for a cost-effective way of doing this? I've got 6500 gp to dump into this (and mundane stuff, but that shouldn't take more than 100 gp). Optimally, I'd prefer stuff that sticks around until triggered or that doesn't have more than a swift action activation, but I'll take what I can get. Feats, class levels, etc are all spoken for, so it's pretty much just the money here.

WotC-published 3.5 only (though material that received an official update outside of Dragon Magazine is legit).

[lordofhalo]

Try using "Roll with this. Hopefully you have toughness and 20 con.

http://dndtools.eu/feats/savage-species--47/roll-with-it--2468/

[Maat Mons]

An amulet of tears (Magic Item Compendium) costs 2,300 gp and lets you expend a charge as a swift action to gain 12 temporary hp for 10 minutes.  It has 3 charges per day, so you could buy two and have 72 extra hp to work with every day.  If your DM allows, you could instead get one with more charges for a proportionally higher cost. 

[Bauglir]

Try using "Roll with this. Hopefully you have toughness and 20 con.

http://dndtools.eu/feats/savage-species--47/roll-with-it--2468/

Savage Species is 3.0, unfortunately. Also I have neither prereq. Con 16. Aberrant Blood (Flexible Limbs), Mounted Combat, Inhuman Reach, Mage Slayer, Exotic Weapon Proficiency (Spiked Chain), Combat Expertise, Improved Trip, and Shape Soulmeld (Mauling Gauntlets). Mounted Combat is a mandatory bonus feat due to Knight levels, but I can lose Shape Soulmeld if I have to, I suppose, but I will set myself on fire and dance a jig off a plane before I spend it on Toughness. The magnitude of the DR is also rather low - I'd prefer higher values that eventually expire, such as might be found on an Iron Ward Diamond armor crystal (though that is denied me because I'm wearing light armor to benefit from that Fighter ACF in Drow of the Underdark).

Thanks for the attempt, though.

EDIT: The amulet sounds like a solid choice. I'll go with a pair, thanks.

[Ithamar]

Can you squeeze in the Stone Power feat?  Take a -1 or -2 to attack and gain twice that amount in temp HP.