"Let your conversation be without covetousness; and be content with such things as ye have" (Hebrews 13:5a).
Contrary to public opinion, you can homeschool your children without spending a large amount of money. Like most homeschooling parents, I considered "cheap" and "free" my favorite two words when looking for curriculum and resources for our homeschool. Many times I was forced to make my own teaching aids for phonics, math, and science concepts. Surprisingly, my children never minded my homemade visuals. In fact, they became inspired to design their own teaching tools for playing games together.
Making the most of what you have is a missionary mindset the apostle Paul illustrated well in Philippians 4:11-12: "Not that I speak in respect of want: for I have learned, in whatsoever state I am, therewith to be content. I know both how to be abased, and I know how to abound: every where and in all things I am instructed both to be full and to be hungry, both to abound and to suffer need." Paul had learned the art of being content no matter what material blessings God provided. At times, God provided for Paul's needs by giving him the opportunity to earn his own living (1 Thessalonians 2:9). Other times, God used the charitable giving of Christians to meet Paul's needs. Whatever the situation, Paul knew God would provide if he was in the middle of God's will, even if God's will placed him in the middle of a sinking ship (Acts 27)!
God promises that you will not lack in the work He has for you to do (2 Corinthians 9:8). If He has called you to teach your children, He already knows the costs involved and the resources you need. Don't get into trouble financially by falling for the bigger and better mentality in regard to purchasing homeschooling supplies. Pray and seek the Lord's choices for teaching your children. Perhaps you're failing to notice the untapped resources He has already given you. Isn't the Bible, the best curriculum any child can use, the best place to start?
Lord, forgive my greediness in wanting homeschooling trips and resources I cannot afford. Open my eyes to see the provisions You've clearly laid before me to teach my children what they need to know. In Jesus' name, Amen.