Do a search for Flash designer and send them a question. That is going to be the easiest thing for you to do. It is going to vary based on what you are looking for for the site. I do coding for a local bank and most developers in our area that freelance get between 25 - 50 an hour, or if it is a smaller site charge a flat fee, but it all depends on what you are looking for.
As far as a monthly maintenance fee, are you looking for updates to the site or the hosting cost? Hosting is generally paid on a yearly basis. Updates can be worked into the initial site cost or done as needed for a flat fee.
Things you want to think about before getting quotes:
Do you want a store front?
Do you want to make the updates or have the developer do? If they build it so you can, it will cost more.
How much flash do you want and is it because it's cool or because it will enahnce your overall site?
How many pages will the site have and what will go on each?
If you hope to draw in customers from search engines, then I would definitely avoid using a flash site (at least a 100% flash site). Flash is great for certain aspects of a web page and I personally like the interactive dynamic it adds to the site.
It does have major drawbacks however. The text contained in a flash site cannot be read by a search engine crawler, in short, this means that your site will not appear in search results, and if it does it will most likely be ranked very low.
I intended to have an all-flash site initially, but then I got more info and realized it is not the best option. You can check out my site (link in sig.) if you would like to see how I balanced the two. I have a basic HTML splash page which contains the meta tags and keywords which will help me show up in search results with links to pages that will help my SEO.
There are then two directions the visitor can take... one to my flash catalogue (meant for prospective retailers of my products) and the other is a web store for single internet buyers.
you can get a lot mpore info if you do a search for SEO (search engine optimization) or flash, or webmaster help/discussion...
Well I suggest that a flash site is great but it also it depends that not everyone has a fast connection and if the site takes too long to load then they would leave, but a flash banner or buttons can add the flash sexyness to a well designed template
I agree with what jlcanterbury said. Just don't have it all in Flash (mix it up). I did this website Jefferey's Restaurant recently and made it half flash and half text. I think they're a pagerank 4 now, and it's only about six months old. The search engines love it because we made it the way they like it.
The best and the cheapest is to post on rentacoder.com or guru.com to have one built. You can get a $5000 site for about $400. The only other expense would be your merchant account set-up and the security certificate (ssl). Once you're rolling, it's about 40 bucks a month for a real merchant acount.
i have my own web design business ..as well as my own t line. I wouldn't recommend using flash for the entire site...i incorporate flash just for photos and things of that nature because it compresses the pictures and therefore reduces load times...nobody likes flash intro pages anymore as well. Plus there's addons for mozilla that can disable flash..if that occurs what will your viewers go to? They'll see a blank page. I also use a secondary company for my e commerce function i used prostores but that's not geared for my audience bigcartel.com does what i'm looking for just fine. I can have up to 5 images per shirt design.
As with the examples JL and Mike have shown, we also broke our site up between a flash and html side (for the biz site), and just put a basic storefront for retail (don't distract your customers, you want the focus on your product). You'll find about 2/3 of your traffic with visit the flashy side, but you want to take care of that remaining third who may have older systems.
For referrals for designers, try posting on the classified section at the bottom of the T-Shirt Forums homepage ... you might get a bite!
graphic designer making/mainting website estimate? 
... "you can't take the sky from me"
