Start up costs would include all expenses that incurred during the process of creating your new business. Your inventory purchases make up part of your cost of goods sold in that section of your return. Website development and travel costs would be startup expenses.

How these expenses are handled:

Up to $5,000 of startup costs paid or incurred can be deducted if the total startup costs incurred don't exceed $50,000. An election can be made to amortize costs in excess of $5,000 over a period of 15 years.

If total startup costs exceed $50,000, the excess over $50,000 reduces the amount you may deduct. For example: If you incur $52,000 worth of startup costs, you can deduct $3,000 ($5,000 - ($52,000 - $50,000 = $2,000)) and amortize the remaining $49,000 over at least 15 years

https://turbotax.intuit.com/tax-tips/small-business-taxes/startup-business-tax-tips/L7SOyYMzr 

Examples may include:

- Market Research

- Travel Costs

- Salaries

- Consulting fees

- Accounting and Legal Fees

- Pre-opening advertising expenses

- Overhead

- Employee Training

- Equipment

- An analysis or survey of potential markets, products, labor supply, transportation facilities, etc.

- Advertisements for the opening of the business.

- Salaries and wages for employees who are being trained and their instructors.

- Travel and other necessary costs for securing prospective distributors, suppliers, or customers.

- Salaries and fees for executives and consultants, or for similar professional services.