Indian Healing Clay Mask
This bentonite clay is the cheapest facial you'll ever get. One 16 oz jar costs about $5-$10 depending on where you buy it and it only takes 1 or 2 tablespoons mixed with water or apple cider vinegar to make an incredible detoxifying mask. The molecules in the mask form a negative electron charge that interacts with the positive charge found in various skin toxins.
You can always pour hot water into a bowl as a makeshift steamer but if you're looking to stock your home like spa, I recommend investing in a proper steamer like this one from Dr. Dennis Gross or this less expensive one from Conair. While I've only personally tried the Dr. Dennis Gross, I have heard great things about the Conair as well. These steamers are not only great additions for skincare routines but they are also useful when you're sick.
An arsenal of essential oils can go along way when it comes to both personal care and home care. You can use them in a diffuser to create a relaxing environment, to create your own bath bombs and products, or even directly on your skin depending on the particular oil. A good starter collection consists of lavender, eucalyptus, rose, sweet orange, and lemongrass.
It's hard to have a full-on spa day without a robe. My recommendation is to pick one that is fluffy, not too heavy but not flimsy, and very soft.
Specialty Facial Tools
Invest in a specialty tool that is tailored for your specific skin conditions. For acne, try a powered cleansing brush or a blue light therapy mask. For anti-aging, try a micro-current device or an infrared light therapy mask.