Sarah,
Procurement of items generally falls into 3 camps: ask for donations, use a consignor, or rent a procurement database.
I talk about what these each are -- and the advantages and disadvantages of each -- in this blog and video post:
www.redappleauctions.com/charity-auction-items-where-to-get/
I haven't used Innovative Event Solutions. They might have ties to consignors ... or they might start calling companies on your behalf ... or they might have a database.
A number of my clients have used a company that offers a procurement database. Some of my them had great success and signed-up to use the service the following year. Others got items, but they weren't as desirable as hoped. (For instance, the hotel donations were West coast, and they preferred East coast.)
It's irrelevant, though, because the vendor I had them use guaranteed my clients would make back 100% of the money they paid for the service. So in essence, the $3500 investment with him was risk-free.
I think that if a company offers that type of guarantee, it's great! There's no reason NOT to make the investment.