There are basically three methods of unlocking a Blackberry or any other smart phones for that matter, the IMEI unlock code method, software unlock or unlocking using a cable (the hardware unlock).

Unlocking with the IMEI unlock codes is the fastest and the safest way to unlock a smart phone, really. Softwares and hardware unlocking are not reliable at all, on the other hand Unlocking with IMEI unlock codes is a genuine method to discontinue your contract legally without voiding your warranty, in fact you can even get the unlock code from your Network provider himself.

1. Ask the Network Provider!
Price: Depending on your account status
Difficulty: As easy as dialing a phone number
Time: Can be instantly (dependant on Verizon Wireless)

Phone Verizon Wireless customer services/ Ask for an unlock code to use foreign SIM cards in your RIM/ - Verizon Wireless should be able to provide the unlock code/ Price is dependent on your account status/ - You may need to pay for the unlock code fee up front/ Your unlock code will be sent to you either by post, email or SMS
Sometimes your Network provider wouldn't provide you with the Unlock code simply because they don't want to lose money by terminating the 2 year contract.

2. From a Local Dealer

Price: Dependant on the retailer ($50 - $100)
Difficulty: Medium
Time: Instantly in store

Find them using your online / telephone directory/ Ask them to unlock your RIM BlackBerry , locked to Verizon Wireless in United States/ Get your RIM unlocked in store using special hardware/ Ensure you back up all your settings and critical data/ You can usually negotiate the price/ The work can be done instantly - while you wait
Usually this is an expensive option depending on the dealer and may take several days depending on the source of unlock codes the dealer is using.

3. Remote Unlock Code Provider

Price: Small Charge.
Difficulty: As easy as dialing a phone number
Time: Instantly to several hours

Use a search engine to locate an online retailer/ Order the unlock code online/ Wait for the unlock code to arrive/ Can be sent by email, SMS or even over the phone/ Follow the instructions and insert the code to unlock.
This is the best option, as few genuine unlock code providers online have reach to the largest databases of unlock codes and hence it is far more safe than the other methods provided only if you're not dealing with a B grade service.

4. Software Unlock

Right now software unlocking is not reliable to unlock your Blackberry. Though there is a self-claimed software solution available, but only for the 8xxx and 9xxx series.
If you're on a budget you may try http://gadgetwidgets.com/freeware-free-unlock-your-blackberry-8000-and-9...
Try at your own risk.

5. Hardware Unlock (unlock clip or unlock box)

Price: Most expensive option (clips usually cheaper than boxes)
Difficulty: Can be technically challenging
Time: Instantly once you have the equipment

Use a search engine to find a suitable online retailer/ Search for RIM BlackBerry unlock clips and/or unlock box/ Order the hardware online/ Get free technical support on the manufacturers website/ Option for additional paid support with many online stores
The most expensive and complicated method out of all.
Not recommended at all.

After going through all the available options, the most reliable, low cost and time saving instant solution to unlock your Blackberry from the comfort of your home. Just get your "Blackberry Unlock Codes"