A shorter, more comprehensible version:

import requests

from bs4 import BeautifulSoup

from urlparse import urljoin

URL = 'http://philadelphia.craigslist.org/search/sss?sort=date&quer...

BASE = 'http://philadelphia.craigslist.org/cpg/'

response = requests.get(URL)

soup = BeautifulSoup(response.content)

for listing in soup.find_all('p',{'class':'row'}):

    if listing.find('span',{'class':'price'}):

        price = int(listing.text[2:6])

        if 100 < price <=250:

            print listing.text

            print urljoin(BASE, listing.a['href']) + '\n'