There’s a tax benefit to doing business the way you do.  You may qualify for a section 179 deduction  worth up to $139,000 for qualified business property placed in service in 2012.  The section 179 deduction is for tangible personal property such as machinery and equipment instead of depreciating them over the useful life of the items.  Section 179 can only be deducted in the year of purchase.

Your home office qualifies as the principal place of business if it is used exclusively and regularly to conduct administrative or management activities of a trade or business and/or store inventory.  There must be no other fixed location of the business where the taxpayer can conduct these activities.  The area claimed can only be used for your business, and not at all for personal use.  You may or may not be able to claim the entire amount.  You can if your gross income from the business is equal or greater than your total business expenses.