was sold. The expenses recognized in this quarter, which would have otherwise been recognized in future periods was approximately $8.8 million. There was a beneficial impact on yard operating expenses due to the change in the GBP to USD exchange rate of $0.4 million.
Operation depreciation and amortization expenses were $9.4 million and $8.5 million for the three months ended October 31, 2010 and 2009, respectively.
Cost of Vehicle Sales. The cost of vehicle sales were approximately $28.2 million during the three months ended October 31, 2010 compared to $24.4 million for the same period last year, an increase of approximately $3.8 million, or 15.5%. Cost per unit sold increased and represented a $5.6 million increase relative to last year. Unit volume decline lead to a reduction of $0.8 million and was due primarily to the migration of certain contracts in the UK from a principal basis to a fee basis. The beneficial impact on the cost of sales due to the change in the GBP to USD exchange rate was $1.0 million.
General and Administrative Expenses. General and administrative expenses, excluding depreciation and amortization, were approximately $27.0 million for the three months ended October 31, 2010 compared to $23.9 million for the same period last year, an increase of approximately $3.1 million, or 12.8%. The growth in general and administrative costs was due primarily to increased advertising costs as we invested in events and media promotions to generate new member activity and technology costs as we continue to modify our IT systems and our seller interfaces. The beneficial impact on general and administrative expenses due to the change in the GBP to USD exchange rate was approximately $0.1 million.
General and administrative depreciation and amortization expenses were $2.3 million and $2.2 million for the three months ended October 31, 2010 and 2009, respectively.
Other Income (Expense). Total other income was approximately $0.6 million during the three months ended October 31, 2010 and 2009.
Income Taxes. Our effective income tax rates for the three months ended October 31, 2010 and 2009 were approximately 37.1% and 38.2%, respectively. The decrease was driven primarily by the geographical allocation of income.
Net Income. Due to the foregoing factors, we realized net income of approximately $37.8 million for the three months ended October 31, 2010, compared to net income of approximately $35.3 million for the same period last year.
Liquidity and Capital Resources
Our primary source of working capital is cash generated though operations. Potential internal sources of additional working capital are the sale of assets or the issuance of equity through option exercises and shares issued under our Employee Stock Purchase Plan. A potential external source of additional working capital is the issuance of debt and equity. However, with respect to the issuance of equity or debt, we cannot predict if these sources will be available in the future and, if available, if they can be issued under terms commercially acceptable to us.
Historically, we have financed our growth through cash generated from operations, public offerings of common stock, the equity issued in conjunction with certain acquisitions and debt financing. Our primary source of cash generated by operations is from the collection on sellers' fees, members' fees and reimbursable advances from the proceeds of auctioned salvage vehicles. Our business is seasonal as inclement weather during the winter months increases the frequency of accidents and, consequently, the number of cars totaled by the insurance companies. During the winter months, most of our facilities process 10% to 30% more vehicles than at other times of the year. This increased volume requires the increased use of our cash to pay out advances and handling costs of the additional business.
Our primary source of working capital is net income. Accordingly, factors affecting net income are the principal factors affecting the generation of working capital. Those primary factors: (i) seasonality, (ii) market wins and losses, (iii) supplier mix, (iv) accident frequency, (v) salvage frequency, (vi) change in market share of our existing suppliers, (vii) commodity pricing, (viii) used car pricing, (ix) foreign currency exchanges rates, (x) product mix, and (xi) contract mix to the extent appropriate, are discussed in the Results of Operations and Risk Factors sections in this Form 10-Q.
As of October 31, 2010, we had working capital of approximately $300.5 million, including cash and cash equivalents of approximately $260.5 million. Cash and cash equivalents consisted primarily of funds invested in money market accounts, which bear interest at a variable rate. Cash and cash equivalents decreased by approximately $7.7 million from July 31, 2010 to October 31, 2010.
We believe that our currently available cash and cash equivalents and cash generated from operations will be sufficient to satisfy our operating and working capital requirements for at least the next 12 months. However, if we experience significant