At eBay, get this Keystone 26" Wall Sleeve for Through-the-Wall Air Conditioners for $24. It's the best price we could find by $60. It's an open-box unit designed to be fastened securely into a wall opening, including pre-cast concrete or masonry walls, before a through-the-wall air conditioner is installed. Buy Now at eBay

At eBay, get the refurb Hisense 8,000-BTU DOE Smart Portable Air Conditioner for $200. It's the best price we could find for a refurb by $30. A 2-year Allstate warranty is included. Buy Now at eBay

This 12,000-BTU mini split system is $391.49 at Walmart.  That's a $59 low.  Shipping is free. Buy Now at Walmart

The Home Depot carries a wide range of portable air conditioners covering small bedrooms up to large open spaces over 700 sq. ft. Prices start around $221 for compact units and climb toward $680 for larger, feature-packed models with heating and dehumidifying functions. Several units are discounted, including one Edendirect model at $449.61, down 41% from $762.04. Shoppers can filter by room size, BTU rating, and features like built-in heaters or dehumidifiers to match a unit to their space. Shop Now at Home Depot

A compact wall-mounted air cooler that suits small rooms or workspaces where you want to free up floor space, it's $99 less than Amazon is charging for a similar one. Import charges of $19.87 and a payment processing fee of $2.08 apply.

New Alibaba customers get shipping for $6.66; otherwise, it starts at around $27.  Buy Now at Alibaba

Keeping a spare motherboard on hand makes sense if your AC's compressor control board fails and you're trying to avoid a full service call, especially once the unit is out of warranty and parts get harder to source. Newegg carries this specific model, which helps if you've already confirmed it matches your external unit's specs. Buy Now at Newegg

Swap these in on a quarterly schedule to keep your HVAC system running cleaner, and the MERV 11 rating traps smaller particles like pet dander and pollen without restricting airflow the way higher-rated filters can. The 4-pack covers a full year of changes, so you're not reordering every few months. Buy Now at Home Depot

This control board suits anyone whose central AC unit has stopped responding properly and needs a direct replacement part rather than a full system repair call. It's a practical fix if you're comfortable handling the installation yourself and want to avoid paying a technician just to swap a single component. Buy Now at Newegg

Anyone running standard HVAC maintenance can stock up here, since a 5-pack covers roughly a year of changes without reordering every few months. Buy Now at Home Depot

Anyone tired of buying replacement filters every few months will appreciate the washable, reusable design here, since it cuts down on recurring costs over time, and it's currently $3.70 off the $36.99 list price at Walmart. Buy Now at Walmart

This vent kit is for anyone running a portable AC unit who needs a proper way to seal the window and keep hot air from leaking back in, and it's currently $31 (52%) off the $60 list price at Walmart. Buy Now at Walmart

Good for cooling a single room without window unit installation, and useful if you need flexibility to move the AC between spaces. At $339.98, that's $100 (23%) off the $439.98 list price. Buy Now at Walmart

Worth a look if you need to cool a larger room since the dual-hose design pulls exhaust air from outside rather than recirculating room air, which tends to cool faster than single-hose units; it's currently $188 off the $660 list price at Walmart. Buy Now at Walmart

Window units this size suit larger rooms or open floor plans where a standard AC just can't keep up, and at $500 it's $639 off the $1,139 list price. Buy Now at Walmart

Small bedrooms or home offices without central air are a good fit for this one, since 10,000 BTU covers roughly 300-450 square feet without permanent installation. Walmart has it for $250, which is $20 off the $270 list price. Buy Now at Walmart

Cooling a single room without a window unit install is the main draw here, which suits renters or anyone needing a portable option they can move between spaces. At $348.80, that's $251.19 (about 42%) off the $599.99 list price. Buy Now at Walmart

Keeping the exhaust hose covered helps block heat transfer and condensation drips, which matters if your portable AC sits in a finished room rather than a garage or basement. It's $4.71 (about 19%) off the $24.70 list price. Buy Now at Amazon

Swapping in a fresh filter this size keeps your HVAC system running efficiently while trapping common household dust and allergens, and MERV 8 strikes a reasonable balance between airflow and filtration for everyday use. Buy Now at Home Depot

Swapping filters every season gets expensive, so having a 3-pack on hand saves you a trip and keeps your HVAC system running without a gap in coverage; MERV 8 is a solid middle ground for catching household dust without straining your airflow. Buy Now at Home Depot

Good for RV owners who need cooling and heat in one rooftop unit without wiring in a separate furnace, and Amazon has it marked down $189 (20%) off the $946 list price. Buy Now at Amazon