Many people like the affordable PARI Trek for travel, available with AC adapter and/or rechargeable lithium battery. Some packages come with a car charger adapter (aka cigarette lighter). Advantages include that it works with my existing neb cups. I found it took a bit longer than the Ombra but it did the job.
https://www.pari.com/us/products/trek-s-portable-aerosol-system/