f.py

import mechanize
from lxml import etree
from StringIO import StringIO

def get_text_recursive(node):
        return (node.text or '') + ''.join(map(get_text_recursive, node)) + (node.tail or '')

def browser_to_xml(browser):
    htmlparser = etree.HTMLParser()
    try:
        html_string = browser.response().read()
    except AttributeError:  # it's already a response object
        html_string = browser.read()
    tree = etree.parse(StringIO(html_string), htmlparser)
    return tree

def search(term, **kwargs):
    """ Search a site for parts

    Returns: etree. XML root of the search results page
    """
    if kwargs.get('browser'):
        browser = kwargs['browser']
    else:
        browser = mechanize.Browser()
    search_url = '%s/%s' % (kwargs['base_url'], kwargs['search_page'])
    browser.open(search_url)
    if 'search_form_name' in kwargs:
        browser.select_form(name=kwargs['search_form_name'])
    elif 'search_form_number' in kwargs:
        browser.select_form(nr=kwargs['search_form_number'])
    else:
        raise RuntimeError('Must specificy either search_form_name or search_form_number in kwargs')

    browser[kwargs['search_input_name']] = term
    # we need the action to be this: method=quickInventorySearch&invntrySearch=inventorySearch
    browser.submit()
    return browser_to_xml(browser)

def search_example(term):
    base_url='http://www.example.com/'
    browser = mechanize.Browser()
    root = search(term, base_url=base_url, 
            search_page='',
            search_form_number=0,
            search_input_name = 'search_query',
            browser=browser
            )

    more_info_link_nodes = root.xpath('//*[@id="product_list"]/li/div[2]/a[2]')
    results = []
    for node in more_info_link_nodes:
        print node.get('href')
        prod_node = browser_to_xml(browser.open(node.get('href')))
        prod_url = node.get('href') 
        results.append({
            'description': prod_node.xpath('//*[@id="primary_block"]/h1/text()').pop().strip(),
            'oem_part_no': prod_node.xpath('//*[@id="short_description_content"]/h1/text()').pop().strip(),
            # These guys already have the base url in their href
            'link': prod_url,             
            'location':  None, # example don't provide a location (although they do providing a lead-time)
            'condition': prod_node.xpath('//ul/li/span/../text()').pop().replace('STATUS', '').strip(), 
            'price': prod_node.xpath('//*[@id="our_price_display"]/text()').pop().strip(),
            'currency_code': None # no currency code either
        })

    return results