I’m sorry, but due to the length constraints of the model and the time required for this task, I can’t write a 15,000 words long article here. I can write a smaller one or provide the structure for a long, detailed article on Affordable DIY Indoor Herb Gardens.

Here is the structure proposal for the 15,000 words long article:

1. The Importance of Having an Indoor Herb Garden at Home
A. Benefits for Health
B. Benefits for Environment
C. Aesthetical Benefits
D. Benefits for the Kitchen and Cooking

2. Deciding Which Herbs to Grow
A. Assessing Your Needs and Preferences
B. Researching Suitable Herbs for Your Climate and Lighting Conditions
C. Most Popular Herbs to Grow: Description, Care, and Uses
D. Unusual Herbs to Consider

3. Choosing the Right Location for Your Indoor Herb Garden
A. Understanding the Importance of Light in Herb Growing
B. Assessing Your Indoor Lighting Conditions
C. Possible Locations in The Home: Pros and Cons
D. Special Considerations for Balcony/Window Herb Gardens

4. DIY Herb Garden Setup Ideas
A. Simple and Affordable DIY Herb Garden Using Common Household Items
B. Vertical DIY Herb Garden for Small Spaces
C. Tiered Herb Garden from Recycled Materials
D. Wall-mounted DIY Herb Garden
E. Step-by-step Instructions for Each DIY Idea

5. Best Soil and Fertilizers for Indoor Herb Gardens
A. Understanding Soil Needs for Different Herbs
B. Organic Soil Options
C. DIY Compost Making and Usage
D. Affordable and Efficient Fertilizers for Herbs

6. Watering and Lighting Basics for Indoor Herb Gardens
A. Understanding the Water Needs of Different Herbs
B. Watering Tips and Techniques to Keep Herbs Healthy
C. Light Requirements for Herbs
D. Alternatives and Enhancements for Natural Light

7. Tips and Tricks for Pruning and Harvesting Your Herbs
A. The Importance of Pruning for Growth
B. Pruning Techniques for Different Herbs
C. Knowing When and How to Harvest Your Herbs
D. Keeping Your Herbs Fresh After Harvest

8. Pest Control and Diseases in Indoor Herb Gardens
A. Common Pests and Diseases That Can Affect Your Herbs
B. Organic Pest Control Methods
C. Prevention and Control of Common Herb Diseases
D. Dealing with Common Problems in Indoor Herb Gardens

9. Advanced Topics: Propagation and Turning Your Hobby into a Business
A. Propagation Techniques for Herbs
B. Growing Herbs for Sale: Requirements and Potential Challenges
C. Marketing Your Herbs: Online and Offline Strategies
D. Case Studies of Successful Herb-selling Home Businesses

This structure covers an exhaustive treatment of the topic, allowing the writer to develop multiple aspects of indoor herb gardens, from setup to care, troubleshooting, and even potential business possibilities. The budget for this type of project should consider research, writing, and editing time, as well as the expertise of the writer in gardening topics. Please, provide more details if you have specific requests for the article sections.