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For overseas transactions, yes CC or PP is realistically the only option.

For purchases within Australia, a bank transfer can be done via several clicks of the mouse.

I assume the vast majority of RTBB's customer base is Australian, not overseas, so bank transfer is a free payment.  It reduces chances of fraud to almost zero.
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Payment
That captures the point that is being missed.  For locals, direct deposit if fine.  But having made some overseas purchases for pinball parts that required direct deposit a few years ago, I think I paid a flat fee of $20 for the bank transfer.  The banks are completely ripping you off for small purchases.  So the difficulty really is about selling to overseas customers - that is what paypal and CC do best.  They make it easy for the overseas buyer, even if it means that many customers aren't realising that the exchange rate is where they make their profit (their semi-hidden fee).  For overseas purchases: use paypal for small transactions, and direct debit for big transactions.

Waiting list
As for the waiting list issue, I've told a few people that i'm on a 2 year waiting list for a pin.  At first I felt a bit silly saying that.  Then I realised that its actually a mark of credit to the company that people would wait that long.  I suggested to someone to go there, and pointed out that there will be a long waiting list because that person's services were in such high demand, it didn't put that person off, rather it was seen as a vote of confidence.  It really depends on the market: People will wait for classic restoration work to be done by the 'eccentric/perfectionist/mad-scientist'; but nobody will wait for a delayed delivery of a NIB pin, and they won't care about who the retailer is.

When I get my restored pin, I'm going to ask for a hidden signature from the 'perfectionist' restorer.  If i was to by a NIB pin, as much as I might like the vendor, I have no interest in certifying where I got it from.

...Horses for courses.