"Thank you for the interest you have shown in me. With regard to the current home project you have assigned me to progress in the interviewing process, I cannot

"Thank you for the interest you have shown in me. With regard to the current home project you have assigned me to progress in the interviewing process, I cannot but feel it's somewhat excessive with regards to my time, while being completely free and noncommittal for you. On the other hand, I certainly understand that you must vet that candidates can actually produce quality software before extending an offer. I believe we can reach a reasonable understanding where I am compensated at my standard consulting rate of $150/hour for any project or homework you might have. This way, the process becomes fair with my time and it also gives you the possibility to thoroughly test my abilities by risking no more than a token amount. Thank you, eagerly awaiting your response."