I did a quick search and found that Rough Country has a Adjustable Shackle for about $50.  It includes 4 bolts with locking nuts included.  http://www.roughcountry.com/jeep_xj_shackles.html

Rusty's Offroad also sells the Daystar greasable shackle hardware/bushings, that are actually a bit more, at about $52.  http://rustysoffroad.com/mm5/merchant.mvc?Screen=PROD&Product_Code=KJ02026BK&Category_Code=LEAFACC

Quadratec also has a warrior kit similar to the Daystar.  Didn't check if Motion carries anything similar.

If your friend is looking for the cheapest possible way out, or maybe the fastest, then I would think, that any grade 8 bolt (and grade 8 rated locking nut) of the appropriate length and diameter should be more than adequate for the application.

Hope this helps.

I think rockauto.com has small parts like that. I also think those are a higher-grade of metric, not a normal grade 8. In a pinch though, the biggest grade-8 that fits would probably work just fine.

Just a brief update.
I went out, just to appease my own curiosity, and checked the marking on the stock bolts. The are identified as "I 9.8". The "I" indicates the manufacturer or the agency spec that the bolt has been tested against, I would assume that in this case the "I" stands for ISO. But, the bolt class is 9.8.

from : http://www.sizes.com/tools/bolts_metric_standards.htm
Class 9.8 is approximately 9% stronger than equivalent to SAE J429 Grade 5 and ASTM A449
Class 10.9 is approximately equivalent to SAE J429 Grade 8 and ASTM A354 Grade BD

There are some differences in metallurgy if the Class is underlined vs. if it is not, in this case it is not.
from : http://euler9.tripod.com/bolt-database/22.html
not underlined - medium carbon steel, quenched and tempered
underlined - low carbon boron steel, quenched and tempered

I would have to conclude that based on the above, a Grade 8 bolt would be more than adequate for the intended use.