There are plenty of after market radiator alternatives far cheaper than
$325...  Do a Google search and get a new unit.

Is that $326 for just the part or parts and labor? If it's just
the part, consider:

1.
An online new OEM radiator purchase from a place like
http://www.hondaautomotiveparts.com/auto/jsp/mws/catdisplay.jsp ?
They want around $250 (add another $20 or so for S/H) for a new
radiator for one of the 91 Civic SI radiators I looked at. Labor
of course will bring this up to a higher cost, unless you are a
DIY-er. http://www.hondiscountparts.com/ looks to  have even
better prices ($117-$158, with free shipping over $50).

2.
A local or online salvage yard? Many yards have online search
engines that are very precise. I used www.olstons.com this past
year for a new crankshaft pulley. The transaction went really
well. The part was just fine.

Seems like there have been a fair number of posts here over the
years about failed radiators for early 1990s Hondas. I can add
that, while a dealer shop was diagnosing what turned out to be a
distributor rotor problem on my 91 Civic LX 4-door sedan, they
broke the top of my car's radiator. I didn't get the details.
They just explained this to me when I went to get the car, adding
that I'd got a free, new radiator out of the deal. (But
considering what they charged me for the rotor problem... oh
never mind. It was still less than the cost of a new radiator.)

There is probably no repair for the tank you have. Something caused it to
crack in the first place - probably erosion on the inside.

A good radiator shop can and will replace tanks on many radiators, assuming
the core is in good shape. My Volvo had plastic tanks, and my favorite rad
shop replaced the cracked top tank with a good metal one and rodded the core
for $75, cash and carry. (I did the removal and installation.) A decade
later it is still doing a good job.

Mike

I've done 2-3" brazing (on my Civic) using a radiator solder core with
great results. I'll bet very few shops are willing to repair it.