Below are a few possibilities around Sannomiya station.

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Some reference points:
★★★: most expensive
★★: relatively less expensive
★: least expensive

Hotel Tor Road★★★
http://www.hoteltorroad.co.jp/

Hotel Monterey Kobe★★★
http://www.hotelmonterey.co.jp/cgi-bin/portal/cms/hotelindex.cgi?hid=monkob

Kobe Sannomiya Union Hotel★★
http://www.unionhotel.jp/

Apa Hotel Kobe Sannomiya★★
http://www.apahotel.com/hotel/kansai/12_kobesannomiya/index.html

Hotel 1-2-3 Kobe★
http://www.hotel123.co.jp/kobe/index.html

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For more possibilities, the following search links would be useful, if you're familiar with Japanese websites:
Jalan
Rakuten Travel
Ikyu.com