Barb,
The key to success is affiliate programs - it's better than SEO optimization, PPC and whatever else you can think of. Nothing can compete with having hundreds of sites selling your product - (profit = leverage).
Do you know the conversion rate on your "front end" ebook? If it's over 1%, start with Clickbank - I'd put together a simple one-pager website with your "front-end" ebook and get it out there. If it's <1%, keep tweaking your sales letter - adding bonuses is usually the easiest way to boost conversion.
From there, start surfing and put together a list of "companion" web sites that your target market would probably visit. Contact those webmasters and let them know about your affiliate program and how much commission you pay (I'd go with at least 50%). You can just email them (low conversion) or look up their physical mailing address with a "whois" service and send them a letter (much better conversion).
I don't know zip about diaper cakes (honestly, the first mental image I had wasn't pretty
- but your website clarified your offering...) - but it looks like a good market.
For more info, Google "Marlon Sanders" - he's the master of affiliate programs and was one of the first guys to use them in internet marketing.
Good luck!