Not sure if this was posted already, and it kinda goes over the $50 mark (if you choose to buy a new condenser as well). Here is a lil tip on how to replace those shibby old ignition coils on your bike that I found on the HondaTwins forum. I did it on the CB360 and it works pretty damn well...
Aftermarket Coils - Honda CB450
On my latest project, a CB450, it was apparent the coils I had around were less than desirable.
I had three pairs, all were well funkified. I had my doubt they had much life left in them.
New coils are a good investment on any old bike, unless you’re doing a persnickety restoration and need to be original.
Something similar could be done for 350's and other 180-degree twins as well.
For the 360-degree twins (like 175/200), aftermarket coils are available as a bolt-up, using 1/2 of a 4-cylinder coil setup.
Not wanting any trouble in the ignition, I bought a pair of Yamaha XS650 Replacement units from http://www.mikesxs.com/
$24 each, quick and cheap shipping.
They only had the yellow wires in stock.
I had to fabricate a couple of little plates to fasten them to, so I could use the stock coil mount, which is the best location. The plates are sort of notched to move the coils as far in towards each other as I could. Space on the sides is limited when the fuel tank is mounted.
You have to tweak the positioning with spacers. Note the use of stacks of washers as spacers - didn’t have any spacers, but I did have a big ol’ sack-o-washers (stainless yet). Someday I might cut some proper spacers.
No place for the condensor , I just drilled a hole in the frame nearby and mounted it there.
I ran a series of 10-gauge ground wires from the battery itself to all the ignition components. So there won’t be any troubles with grounding.
Had to make up a couple of bullet connector “doublers” to accommodate the coil/point/condensor wiring.
Coil wiring was simple - I ran both brown coil wires to the black/white wires from the harness, then used the “doublers” to connect each orange coil wire to either the yellow or blue ignition wires.
All in all, it wasn’t too bad. About $60 for brand new coils, replaceable wires, and plug caps. All I used was a drill, hacksaw, and grinder.
I now have spark that will knock you on your butt, and it’s one less thing I’ll have to worry about on a really old bike.
Seems to me you could do pretty much the same thing on a 350, it’s built pretty much the same.
And I already did it on a CB200 - CB200 is a 360 degree engine (like a 175), only one point, so a single coil with two plug wires. For that one I bought(on EBay) half of a Honda four replacement coil set - it bolted right up, no modifications required.