With buyers encouraged by a federal tax credit that expired in April, Clark County home sales grew by 61.2 percent last month, a burst of activity some real estate agents expect to hold steady through summer.There were 598 houses sold here in April, 227 more transactions than the 371 home sales in the same month last year, according to the “benchmarks” report, released Wednesday by Vancouver-based Riley & Marks appraisal firm. April was the eighth consecutive month that sales were higher than the same month a year ago.Home prices in April, however, continued to soften, bogged down by a flood of bargain-priced foreclosure and short-sale properties. Foreclosures are owned by the bank and sold to the highest bidder. Short sale properties are sold by upside-down borrowers who negotiate to sell for less than they owe on the mortgage.Clark County’s median sale price — half sold for more, half for less — in April was $205,500, a decrease of 5.8 percent when compared with the median of $218,250 one year ago. In some cases, sellers refused to let go of the notion that their homes were still worth the values assessed during the housing boom that ended in 2007, said Jerry Rolling, a sales agent with Keller Williams Realty in Vancouver. As they held out for a higher sales price, values continued to erode.“So many people lost so much because they wouldn’t price it right,” he said.Despite the tax credit’s April 30 expiration date, Rolling and other real estate agents expect local home sales to continue posting high totals through the June, typically the busiest time of the year for residential sales, because supply is shrinking and demand remains strong as the economy improves.