房子换girder, joist, 需要多少钱？

准备买一座53年的独立平房，1200尺, on crawlspace。

Home inspection 发现有结构问题，主要是一层的大梁(girder)和托梁(joist)年久腐烂，需要换。

请问大家，这样的房子能买吗？如果买下，需要多少钱来修复？

Home inspection 报告内容如下。

First floor structure: 

Condition: worse than average. 

Description: 

- Wood girders supporting joists, which in turn support the subfloor. The shorter of the two girders is badly rotted, and portions of the sill plate (2 x 6 sitting flat on top of the block wall) are rotted. Rotted wood should be replaced, including this girder, the sill plate and some of the nearby joists. 

- Determining the full extent of the problem will require many hours of careful investigation, and may include removal of some of the thermal insulation products to view the subfloor. This inspection can reveal that a problem is present, but cannot prescribe exact repair methods, amounts or specifications. 

- The damage seen will require the services of an experienced contractor.

- Insect damage noted on joists.

- Hole in bedroom closet floor, front left corner of the house. The entire floor of this bedroom shows slight warping of the hardwood, a result of excess humidity in the crawl below. The subfloor in the corner is rotted over a fairly wide area. Portions of this floor may collapse under load.