The Sarrafon Guesthouse is a great budget option in Bukhara. They have a 24 hour front desk, can help arrange tours, a great location near the Lyab-i Hauz,and serve a traditional Uzbek breakfast each morning. That said, like many budget hotels/hostels in Uzbekistan, they do not take credit cards.
Click here to book at the Sarrafon Guesthouse on Hostelworld.com.