If you need a highly professional product I suggest to check out Conwin's inflators: http://www.conwinonline.com/shop/index.asp?cid=i. The prices range from $180 to over $1000.
If you are looking for a cheaper alternative, that is still doing a good job, you could do a search for "balloon inflators" at ebay. The "Qualatex Mini Cool Air Inflator" for example, is on offer for $142.95. It's similar to the inflator we use ourselves and we are happy with our model.
