The market continues to sell off, and bank and financial service company stocks have been among the hardest hit. However, I believe that instead of being a cause for panic, now is an excellent time to get into some great companies that are on sale.

Here's a look at three of them, each of which produced very good results this quarter and might be worth a look while the discounts last.

A great, cheap bank just got even cheaper
Bank of America
(NYSE:BAC) posted an excellent quarter when it reported earnings on Wednesday, yet shares sold off even worse than the rest of the market. Shares lost about 5% in the day following the earnings announcement and are down by about 10% over the past couple of weeks.

However, look at the positives here. The company beat revenue expectations, and aside from the Justice Department settlement it had to pay, it turned a nice profit. The company grew in a few ways that should pay off in the future.

For example, client brokerage assets rose by more than 20% year over year and saw positive inflows. During the third quarter alone, the company issued 1.2 million new credit cards, the majority of which were issued to Bank of America's current customers. This could really pay dividends down the road, as the bank doesn't make money when the cards are issued, but as the balances on those cards grow over time.

Despite the growth, Bank of America trades for just 10.5 times next year's expected earnings and trades for just 1.15 times its tangible book value, which, as you can see, is the lowest level in about two months.

BAC Price to Tangible Book Value Chart

Rock-solid banking at a discount
Wells Fargo
(NYSE:WFC) didn't beat the market, but it did meet expectations, only to see its shares drop anyway. In fact, Wells Fargo, which is considered a very low-volatility, rock-solid banking play, lost 5% in the two days following the earnings report and have dropped by more than 11% over the past month.

The numbers look pretty solid, with 4% year-over-year revenue growth and a higher efficiency ratio. The bank's auto lending, credit card, and commercial banking lending businesses all grew at double-digit annual rates.

The bank's asset quality, which was very strong to begin with, keeps getting better. Its charge-off ratio is a mere 0.32%, and the dollar amount of charge-offs fell by 33% since the same quarter last year.

In short, Wells Fargo is growing in all the right ways and is still the best-in-breed among the big U.S. banks. And its share price is the cheapest it's been since May.

WFC Chart

The best in payment processing is on sale
American Express
(NYSE:AXP) beat the market's expectations on earnings, but missed on revenue.

The company saw a 9% year-over-year increase in card spending, and a 5% increase on the total outstanding loan balance on its cards. While the international business lagged a little, the U.S. card business was especially strong, with 14% higher revenue than a year ago, with just a 2% increase in total expenses.

Sure, the high international exposure is a legitimate cause for concern, especially considering Europe's economic issues, but it is definitely a great opportunity to profit once the economy in Europe starts to improve. And in the meantime, the company has a rock-solid U.S. business to make money from.

American Express also has recently announced partnerships with Apple Pay, Uber, and McDonald's, all of which should provide a nice boost to revenue, especially if Apple Pay lives up to its potential.

One of the biggest reasons to jump into AmEx is how much the stock has fallen. Since July, it has lost 16% of its value, despite the impressive growth the company is experiencing.

AXP Chart

AXP data by YCharts

One of the best ways to create real wealth as an investor is to buy great companies at a good price, and the recent market sell-off has created a great opportunity to do just that.