Hey Marcie,
I've used Digesto from Pekuto before - It's a relatively straightforward solution and the price was very reasonable.
Please allow me to suggest considering going a different direction...
If you're still unsure as to whether or there is any value in doing this at all ("will anyone even subscribe to our blog") then I'd suggest that any implementation/integration you go and do is going to cost you more time/money than you presently believe is worthwhile.
In order to test whether or not you should be looking for a long-term solution, may I suggest that you create a program template for a blog update, collect subscribers and manually clone the program, edit the email and send it for the first few months.
Once you've got the program in place, it shouldn't take you more than half an hour per email including sending, and if you're doing an email a week you're talking about a 2 hour time investment per month during your testing period.
Once you've done that, and you've seen that people do in fact subscribe, and that they also respond to your emails, you'll be able to determine whether you actually need a tool to automate the process, or whether the hands-on approach is a viable option for you at the moment.
This way, when you want to choose a tool, you won't be worried about the cost because you know there'll be a value 
Hope this helps
--Guy