When talking about poor but fun seaside attractions, here are some suggestions:

1. Azores: This Portuguese island group is located in the Atlantic Ocean, with spectacular beaches, volcanic landscapes and rich marine life. The transportation and accommodation here are relatively cheap, which is suitable for poor travelers.

2. Da Nang: Xian is located in the middle, with beautiful beaches, spectacular mountains and unique cultural landscape. The food and accommodation here are relatively economical, and it is a popular destination for poor travel.

3. Boracay: Boracay is one of the most popular beach resorts in the Philippines, with white beaches, clear waters and abundant water activities. Although there are some high-end resorts, you can also find some economical accommodation options.

4. Krabi in Thailand: Krabi is located in the south of Thailand, with spectacular islands, beaches and coral reefs. There are many affordable accommodations and local cuisines here, which are suitable for poor travelers.

5. Bali: Bali is one of the most popular tourist destinations, with beautiful beaches, temples and unique culture. Although there are some high-end resorts, you can also find some affordable accommodation and local restaurants.

These places offer beautiful beaches and rich natural landscapes, as well as some economical accommodation and dining options. Remember to make budget planning and reasonable arrangements in advance to ensure that your trip is pleasant and economical.