St John St Cycles/Thorn in the UK have 155mm stoker cranks, 110/74 BCD 5-bolt in square taper for $154 right now. The Thorn brand is perfectly good and SJS are reliable and long established. These are not really flash hi-tech cranks but they are solid and look nice on the bike. The 74 BCD is standard for a road triple inner ring. The most common 110 BCD rings these days are 34T and 50T 'compact' road rings, which are not horribly expensive in say Tiagra if you shop around, or your current rings may transfer directly.
Only thing ya gotta watch is that SJS do not always pick the most economical postage option when sending stuff overseas.
Lots of tandems have 38T timing/sync rings. A 110 BCD 38T ring might be pretty hard to find if you currently have a 130 BCD rear sync crank. Tandems East and other specialty shops have options I imagine, if you call. SJS sell a very spendy Middleburn. My Fuji uses 39T timing rings, so I needed a 39T 110BCD chainring to set up the kiddy-crank - I just got a TA Zephyr from Wiggle for about $50 - it is a lovely ring but not exactly cheap!
You may be able to sell your old cranks for a decent price to offset the costs.
Let us all know what happens, and post a picture too!