My US tax knowledge is a bit rusty but...
Expenses are deductible if they are ordinary and necessary expenses of carrying on a trade or business. Whether something is ordinary and necessary is based upon the facts. An expense is necessary if it is helpful to your business and ordinary if it is one that is common and accepted in your particular activity.
To get an exact answer you would need to read some tax cases for precedents.
Are you an employee? If so the expense is subject to the 2% of AGI limitation for miscellaneous itemized deductions. I hope that either you have other such expenses or your income is greater than $15,000.