Like @Pug27, my 650's recent service at 13,000 miles included valve check, plugs, oil and filter and cost me £380.
There seems to be some confusion about service intervals though - mine had a service at 7,500 when I bought it and I was told the next was due at 12,500, but my local Suzuki dealer said it wasn't really needed until 16,000 (this was when I dropped it in for it's service)
I was given an SV650 as a loaner bike - man it's so different to the strom, tiny, fast, uncomfortable but really good fun despite the pouring rain!