Steve,
First...one of the bright spots I saw in the initial Kindle release was the ability for author's to electronically self-publish with them. Of course you already can do that via other software. But here you can gain exposure with a site like Amazon. Nice.
Next, as far as promotions...yeah paying someone to do it can be expensive without a doubt. BUT, you are in a smaller market and while there is competition it's not as difficult to get on that first page above the fold doing it yourself.
For about a decade I have used a program off and on for client sites as well as a former smaller market business I created online. It helped we were an early adopter of selling and offering information online but still there was competition.
I found a free, at the time, program called
WebCEO (Web Search Engine Optimization). It worked great as it also blasted info out to many of the very obscure niche & freak web search engines. We shot up to the number one result from Google for the two years I stayed on top of it and before my biz partner filed personal bankruptcy and took the biz down with him. Not really his fault but he never gave me a chance to buy him out, even under the table. bad advice from his attorney.
But anyway, it's an excellent package and I see they still offer a free version to try out. They top end product is not very pricey at all.
Getting outside of Google, Yahoo, MSN and whoever are also not a bad thing for a business. There are MILLIIONS of people who simply find these smaller search engines more within their comfort zone.
The software also helps optimize with the major search engines also...
Last, why can you not join the Amazon Affiliate program and promote your books that way, rather than directly? That would reduce the effective overhead of Amazon's cut. If need be put in your better-half's name or a good buddy.
But, it will be interesting to see how this all pans out for author's such as yourself. I can see it catching on even with established authors. They already have a name they no longer need the big publishers, specially so for ebooks.
Anyway, this might all have already been apparent to ya...but thought I would pass it along...we need you guys to eat regular so we have new stuff to read.