Find the cost of a new one identical to yours. Figure 50-75% for a used one, depending on condition, caiber etc. In this case you are probably looking at closer to 75% if it is the Hawkeye which came out in 2006. Probably a little less if it is the MK-II. The Hawkeye had a few improvents, especially the trigger which should help value. Sometimes it doesn't hurt to start a little high, you can always come down.
A budget scope adds about 25-50% of a new scopes value.
A new rifle is about $650, the scope $200 so I'd guess $450-$500 for the rifle, and $50-$100 extra for the scope.
Call it $500-$600 for the package if it were the Hawkeye, about $50 less if not. A lot varies by region, time of the year and other conditions but that is a ballpark figure for where I live in late June. Might bring a little more closer to hunting season. A little more or less in other parts of the country.